OKS Oneok Partners, L.P.

DESCRIPTION OF NOTES

The following description is a summary of the material terms of our notes. The descriptions in this prospectus supplement and the accompanying base prospectus contain a description of certain terms of the notes and the indenture under which the notes will be issued but do not purport to be complete, and reference is hereby made to the indenture that is an exhibit to the registration statement of which this prospectus supplement and the accompanying base prospectus are a part and to the U.S. Trust Indenture Act of 1939, as amended. This summary supplements the description of debt securities in the accompanying base prospectus and, to the extent it is inconsistent, replaces the description in the accompanying base prospectus. We urge you to read the indenture because it, and not this description, defines your rights as a holder of the notes. The following description of the notes and the description of the debt securities contained in the accompanying base prospectus are not complete and are subject to, and are qualified in their entirety by reference to, all the provisions of the indenture. You may request a copy of the indenture from us as set forth under “Where You Can Find More Information” below. Whenever particular defined terms of the indenture are referred to, those defined terms are incorporated herein by reference. In this “Description of Notes,” references to “we,” “us” and “our” refer to ONEOK, Inc. and not to any of its subsidiaries.

General

Each series of notes will be issued under a senior indenture (as amended and supplemented from time to time, including supplements setting forth the terms of the notes) among us, ONEOK Partners, the Intermediate Partnership and U.S. Bank National Association, as trustee (the indenture, as supplemented, is referred to as the “indenture”).

The notes will be senior debt securities that will be our direct, unsecured obligations and will rank equally with all of our existing and future unsecured senior indebtedness. The notes will be guaranteed by ONEOK Partners and the Intermediate Partnership, two of our subsidiaries, however, such guarantors will not otherwise be subject to the covenants, obligations and duties provided for in the indenture solely in their capacity as guarantors. Each guarantee will rank equally in right of payment with all of such guarantor’s existing and future unsecured senior debt and their other unsecured guarantees of senior debt. The notes will be structurally subordinated to all existing and future debt and other obligations of our non-guarantor subsidiaries and will be effectively subordinated to all of our and the guarantors’ future secured debt to the extent of the value of the collateral securing such debt. Assuming we had completed this offering on December 31, 2019, after giving effect to the application of the net proceeds as described in “Use of Proceeds” in this prospectus supplement, the notes and the guarantees would have been structurally subordinated to approximately $21.3 million of outstanding indebtedness of our non-guarantor subsidiaries.

We will issue the 2025 notes in an initial aggregate principal amount of $400,000,000. We will issue the 2030 notes in an initial aggregate principal amount of $850,000,000. We will issue the 2050 notes in an initial aggregate principal amount of $400,000,000.

We will issue the notes in minimum denominations of $2,000 and whole multiples of $1,000 in excess thereof.

Because we conduct our operations through our subsidiaries, our ability to service our debt, including our obligations under the notes, and other obligations are dependent on the earnings of our subsidiaries and the payment of those earnings to us in the form of distributions, dividends, loans or advances from our subsidiaries or the repayment of loans or advances from us by our subsidiaries. Any payment of distributions, dividends, loans or advances by our subsidiaries could be subject to statutory or contractual restrictions. Our non-guarantor subsidiaries and affiliates have no obligation to pay any amounts due on the notes.

The notes will not be subject to a sinking fund provision.

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The notes are subject to defeasance at our option as provided in the indenture. Unless we redeem the 2025 notes prior to maturity, the entire principal amount of the 2025 notes will mature and become due and payable, together with any accrued and unpaid interest thereon, on September 15, 2025. Unless we redeem the 2030 notes prior to maturity, the entire principal amount of the 2030 notes will mature and become due and payable, together with any accrued and unpaid interest thereon, on March 15, 2030. Unless we redeem the 2050 notes prior to maturity, the entire principal amount of the 2050 notes will mature and become due and payable, together with any accrued and unpaid interest thereon, on March 15, 2050.

The indenture does not contain provisions that afford holders of the notes protection in the event we are involved in a highly leveraged transaction or other similar transaction that may adversely affect such holders. The indenture does not limit our ability to issue or incur other unsecured debt or issue preferred stock.

Interest

Interest on the 2025 notes will accrue at 2.200% per annum from March 10, 2020, interest on the 2030 notes will accrue at 3.100% per annum from March 10, 2020 and interest on the 2050 notes will accrue at 4.500% per annum from March 10, 2020. Interest on the notes will be payable in U.S. dollars semi-annually in arrears on March 15 and September 15 of each year (each, an “Interest Payment Date”), beginning on September 15, 2020 and at maturity or, if applicable, earlier redemption. Interest payable on an Interest Payment Date will be paid to the person in whose name the note is registered at the close of business on March 1 or September 1, as the case may be (whether or not a business day in the City of New York), immediately preceding such Interest Payment Date.

Interest payable at maturity or earlier redemption will be paid against presentation and surrender of the related notes. Interest on the notes will be computed on the basis of a 360-day year consisting of twelve 30-day months.

If any Interest Payment Date, the maturity date or any redemption date is not a business day in New York, New York, the required payment shall be made on the next succeeding day that is a business day as if it were made on the date such payment was due and no interest shall accrue on the amount so payable for the period from and after such Interest Payment Date, maturity date or redemption date, as the case may be, to such next business day.

Optional Redemption

On or after August 15, 2025 (one month prior to their maturity date), we may redeem the 2025 notes, in whole or in part, at any time and from time to time, on at least 15 days, but not more than 60 days, prior notice mailed to each holder of the 2025 notes to be redeemed, at a redemption price equal to 100% of the principal amount of the 2025 notes being redeemed plus accrued and unpaid interest to the redemption date. On or after December 15, 2029 (three months prior to their maturity date), we may redeem the 2030 notes, in whole or in part, at any time and from time to time, on at least 15 days, but not more than 60 days, prior notice mailed to each holder of the 2030 notes to be redeemed, at a redemption price equal to 100% of the principal amount of the 2030 notes being redeemed plus accrued and unpaid interest to the redemption date. On or after September 15, 2049 (six months prior to their maturity date), we may redeem the 2050 notes, in whole or in part, at any time and from time to time, on at least 15 days, but not more than 60 days, prior notice mailed to each holder of the 2050 notes to be redeemed, at a redemption price equal to 100% of the principal amount of the 2050 notes being redeemed plus accrued and unpaid interest to the redemption date.

Prior to August 15, 2025 (one month prior to their maturity date) in the case of the 2025 notes, prior to December 15, 2029 (three months prior to their maturity date) in the case of the 2030 notes and prior to September 15, 2049 (six months prior to their maturity date) in the case of the 2050 notes, the notes of each

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series will be redeemable, in whole or in part, at any time and from time to time, at our option, at a redemption price equal to the greater of:

plus, in each case, accrued and unpaid interest on the notes to the redemption date.

The quotation agent means the reference treasury dealer appointed by us to serve in that capacity. The term reference treasury dealer means each of Barclays Capital Inc., Deutsche Bank Securities Inc., Mizuho Securities USA LLC and TD Securities (USA) LLC and their respective successors. If, however, any of Barclays Capital Inc., Deutsche Bank Securities Inc., Mizuho Securities USA LLC or TD Securities (USA) LLC ceases to be a primary U.S. government securities dealer in the United States, we will substitute another primary treasury dealer, as applicable.

The adjusted treasury rate means, for any redemption date, the rate per annum equal to the semi-annual equivalent yield to maturity of the comparable treasury issue, assuming a price of the comparable treasury issue (expressed as a percentage of its principal amount) equal to the comparable treasury price for that redemption date. The comparable treasury issue means the U.S. treasury security selected by the quotation agent as having a maturity comparable to the remaining term of such notes to be redeemed, assuming the notes matured on the Par Call Date, that would be used, at the time of a selection and in accordance with customary financial practice, in pricing new issues of corporate debt securities of comparable maturity to the remaining term of such notes assuming the notes matured on the Par Call Date. The Par Call Date means August 15, 2025, with respect to the 2025 notes, December 15, 2029, with respect to the 2030 notes and September 15, 2049, with respect to the 2050 notes, the date that is one month, three months and six months prior to the maturity date of the 2025 notes, the 2030 notes and the 2050 notes, respectively.

The comparable treasury price means, for any redemption date, the reference treasury dealer quotation for the redemption date.

A reference treasury dealer quotation means, with respect to any redemption date, the average, as determined by us, of the bid and asked prices for the comparable treasury issue (expressed, in each case, as a percentage of its principal amount) quoted in writing to the trustee on the third business day preceding the redemption date.

In case of a partial redemption, selection of the notes for redemption will be made by such method as the trustee in its discretion deems appropriate and fair and may provide for the selection for redemption of portions of the principal of notes. While the notes are held pursuant to the book-entry system, selection of notes for partial redemption will be made by the depositary pursuant to its practices and procedures. Notice of any redemption will be mailed by first class mail or sent electronically at least 15 days but not more than 60 days before the redemption date to each holder of the notes to be redeemed at its registered address. If any note is to be redeemed in part only, the notice of redemption that relates to the note will state the portion of the principal amount of the note to be redeemed. A new note in a principal amount equal to the unredeemed portion of the note will be issued in the name of the holder of the note upon surrender for cancellation of the original note. Unless we default in payment of the redemption price, on and after the redemption date, interest will cease to accrue on the notes or the portions of the notes called for redemption.

Mandatory Redemption

We will not be required to make any mandatory sinking fund payments with regard to the notes or to redeem any of the notes before maturity.

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Covenants

The notes will have the benefit of the covenants set forth under “Description of Debt Securities—Certain Restrictive Covenants Under Our Senior Indenture” and “Description of Debt Securities—Consolidation, Merger and Sale of Assets” in the accompanying base prospectus.

Guarantees

ONEOK Partners and the Intermediate Partnership will unconditionally guarantee the payment of the notes on a senior unsecured basis, however, will not otherwise be subject to the covenants, obligations and duties provided for in the indenture solely in their capacity as guarantors. Notwithstanding the preceding sentence, ONEOK Partners and/or the Intermediate Partnership will be released from their obligations under the indenture, and its guarantees will no longer be in effect, if such guarantor is (i) no longer our subsidiary or (ii) no longer (x) an obligor on, or issuer of, any capital markets debt securities or (y) a guarantor of any capital markets debt securities issued by us or the other guarantor, in each case other than the notes, so long as no default or event of default under the indenture has occurred or is continuing. In such event, such guarantor will give the trustee notice, and we and the trustee will execute and deliver a supplemental indenture reflecting the release of the guarantee. Such guarantor will also be released from its obligations under the indenture, and its guarantee will no longer be in effect, if either a defeasance or satisfaction and discharge of the indenture occur.

ONEOK Partners’ and the Intermediate Partnership’s guarantees will be senior unsecured obligations of ONEOK Partners and the Intermediate Partnership and will rank equally in right of payment with their guarantees of our $2.5 billion revolving credit agreement, our $1.5 billion term loan facility, our approximately $7.2 billion of notes outstanding (excluding the notes contemplated hereby), our $2.5 billion commercial paper program and certain of our existing and future unsecured senior debt. The guarantee of the notes by ONEOK Partners will also rank equally with its existing $4.1 billion of notes outstanding and certain of its existing and future unsecured senior debt. Additionally, the guarantee of the notes by the Intermediate Partnership will rank equally with its existing guarantee of ONEOK Partners’ outstanding senior notes and any unsecured senior debt that the Intermediate Partnership may guarantee in the future. ONEOK Partners’ and the Intermediate Partnership’s guarantees will be structurally subordinated to all indebtedness of our other subsidiaries.

Events of Default

The notes will have the events of default set forth under “Description of Debt Securities—Events of Default” in the accompanying base prospectus.

Further Issues

We may from time to time, without the consent of existing holders, create and issue additional notes having the same terms and conditions as either or both series of notes in all respects, except for settlement date, issue price and, if applicable, the first payment of interest on the additional notes. Additional notes issued in this manner will be consolidated with, and will form a single series with, the applicable series of outstanding notes. If any such additional notes are not fungible with the applicable series of outstanding notes for U.S. federal income tax or other purposes, they will be issued with a different CUSIP number (or other applicable identifying number).

Governing Law

The indenture and the notes for all purposes shall be governed by and construed in accordance with the laws of the State of New York.

Trustee and Paying Agent

U.S. Bank National Association is the trustee, paying agent and registrar under the indenture and the notes. We maintain customary banking relationships with U.S. Bank National Association.

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Book-Entry System

We have obtained the information in this section concerning The Depository Trust Company (“DTC”), Clearstream Banking S.A., Luxembourg (“Clearstream, Luxembourg”) and Euroclear Bank S.A./N.V. (“Euroclear”) and their book-entry systems and procedures from sources that we believe to be reliable. We take no responsibility for an accurate portrayal of this information. In addition, the description of the clearing systems in this section reflects our understanding of the rules and procedures of DTC, Clearstream, Luxembourg and Euroclear as they are currently in effect. Those systems could change their rules and procedures at any time.

The notes will initially be represented by one or more fully registered global notes. Each such global note will be deposited with, or on behalf of, DTC or any successor thereto and registered in the name of Cede & Co. (DTC’s nominee). You may hold your interests in the global notes in the United States through DTC, or in Europe through Clearstream, Luxembourg or Euroclear, either as a participant in such systems or indirectly through organizations which are participants in such systems. Clearstream, Luxembourg and Euroclear will hold interests in the global notes on behalf of their respective participating organizations or customers through customers’ securities accounts in Clearstream, Luxembourg’s or Euroclear’s names on the books of their respective depositaries, which in turn will hold those positions in customers’ securities accounts in the depositaries’ names on the books of DTC. Citibank, N.A. will act as depositary for Clearstream, Luxembourg and JP Morgan Chase Bank will act as depositary for Euroclear.

So long as DTC or its nominee is the registered owner of the global securities representing the notes, DTC or such nominee will be considered the sole owner and holder of the notes for all purposes of the notes and the indenture. Except as provided below, owners of beneficial interests in the notes will not be entitled to have the notes registered in their names, will not receive or be entitled to receive physical delivery of the notes in definitive form and will not be considered the owners or holders of the notes under the indenture, including for purposes of receiving any reports delivered by us or the trustee pursuant to the indenture. Accordingly, each person owning a beneficial interest in a note must rely on the procedures of DTC or its nominee and, if such person is not a participant, on the procedures of the participant through which such person owns its interest, in order to exercise any rights of a holder of notes.

Unless and until we issue the notes in fully certificated, registered form under the limited circumstances described below under the heading “—Certificated Notes”:

The Depository Trust Company

DTC will act as securities depositary for the notes. The notes will be issued as fully registered notes registered in the name of Cede & Co. DTC has advised us that it is:

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DTC holds securities that its direct participants deposit with DTC. DTC facilitates the settlement among direct participants of securities transactions, such as transfers and pledges, in deposited securities through electronic computerized book-entry changes in direct participants’ accounts, thereby eliminating the need for physical movement of securities certificates.

Direct participants of DTC include securities brokers and dealers (including the underwriters), banks, trust companies, clearing corporations and certain other organizations. DTC is owned by a number of its direct participants. Indirect participants of DTC, such as securities brokers and dealers, banks and trust companies, can also access the DTC system if they maintain a custodial relationship with a direct participant.

If you are not a direct participant or an indirect participant and you wish to purchase, sell or otherwise transfer ownership of, or other interests in, notes, you must do so through a direct participant or an indirect participant. DTC agrees with and represents to DTC participants that it will administer its book-entry system in accordance with its rules and by-laws and requirements of law. The U.S. Securities and Exchange Commission (the “SEC”) has on file a set of the rules applicable to DTC and its direct participants.

Purchases of notes under DTC’s system must be made by or through direct participants, which will receive a credit for the notes on DTC’s records. The ownership interest of each beneficial owner is in turn to be recorded on the records of direct participants and indirect participants. Beneficial owners will not receive written confirmation from DTC of their purchase, but beneficial owners are expected to receive written confirmations providing details of the transaction, as well as periodic statements of their holdings, from the direct participants or indirect participants through which such beneficial owners entered into the transaction. Transfers of ownership interests in the notes are to be accomplished by entries made on the books of participants acting on behalf of beneficial owners. Beneficial owners will not receive certificates representing their ownership interests in notes, except as provided below in “—Certificated Notes.”

To facilitate subsequent transfers, all notes deposited with DTC are registered in the name of DTC’s nominee, Cede & Co. The deposit of notes with DTC and their registration in the name of Cede & Co. effect no change in beneficial ownership. DTC has no knowledge of the actual beneficial owners of the notes. DTC’s records reflect only the identity of the direct participants to whose accounts such notes are credited, which may or may not be the beneficial owners. The participants will remain responsible for keeping account of their holdings on behalf of their customers.

Conveyance of notices and other communications by DTC to direct participants, by direct participants to indirect participants and by direct participants and indirect participants to beneficial owners, will be governed by arrangements among them, subject to any statutory or regulatory requirements as may be in effect from time to time.

Clearstream, Luxembourg

Clearstream, Luxembourg has advised us that it is incorporated under the laws of Luxembourg as a professional depository. Clearstream, Luxembourg holds securities for its customers and facilitates the clearance and settlement of securities transactions between its customers through electronic book-entry changes in accounts of its customers, thus eliminating the need for physical movement of certificates. Clearstream, Luxembourg provides to its customers, among other things, services for safekeeping, administration, clearance and settlement of internationally traded securities and securities lending and borrowing. Clearstream, Luxembourg interfaces with domestic markets in a number of countries. Clearstream, Luxembourg is an indirect participant in DTC.

Clearstream, Luxembourg customers are recognized financial institutions around the world, including underwriters, securities brokers and dealers, banks, trust companies, clearing corporations and certain other organizations. Indirect access to Clearstream, Luxembourg is also available to others, such as banks, brokers, dealers and trust companies that clear through, or maintain a custodial relationship with, a Clearstream, Luxembourg customer either directly or indirectly.

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The Euroclear System

Euroclear has advised us that the Euroclear System was created in 1968 to hold securities for participants in the Euroclear System and to clear and settle transactions between Euroclear participants through simultaneous electronic book-entry delivery against payment, thus eliminating the need for physical movement of certificates and risk from lack of simultaneous transfers of securities and cash. Transactions on the Euroclear System may now be settled in many currencies, including U.S. dollars. The Euroclear System provides various other services, including securities lending and borrowing and interfaces with domestic markets in several countries generally similar to the arrangements for cross-market transfers with DTC described below.

The Euroclear System is operated by Euroclear (the “Euroclear Operator”), under contract with Euroclear Clearance System, S.C., a Belgian cooperative corporation. The Euroclear Operator conducts all operations, and all Euroclear securities clearance accounts and Euroclear cash accounts are accounts with the Euroclear Operator, not the cooperative. The cooperative establishes policy for the Euroclear System on behalf of Euroclear participants. Euroclear participants include banks (including central banks), securities brokers and dealers and other professional financial intermediaries and may include the underwriters. Indirect access to the Euroclear System is also available to other firms that clear through or maintain a custodial relationship with a Euroclear participant, either directly or indirectly. Euroclear is an indirect participant in DTC.

The Terms and Conditions Governing Use of Euroclear and the related Operating Procedures of the Euroclear System and applicable Belgian law govern securities clearance accounts and cash accounts with the Euroclear Operator. Specifically, these terms and conditions govern:

All securities in the Euroclear System are held on a fungible basis without attribution of specific certificates to specific securities clearance accounts. The Euroclear Operator acts under the terms and conditions only on behalf of Euroclear participants and has no record of or relationship with persons holding securities through Euroclear participants.

Euroclear further has advised us that investors that acquire, hold and transfer interests in the notes by book-entry through accounts with the Euroclear Operator or any other securities intermediary are subject to the laws and contractual provisions governing their relationship with their intermediary, as well as the laws and contractual provisions governing the relationship between such an intermediary and each other intermediary, if any, standing between themselves and the notes.

The Euroclear Operator has advised us that under Belgian law, investors that are credited with securities on the records of the Euroclear Operator have a co-property right in the fungible pool of interests in securities on deposit with the Euroclear Operator in an amount equal to the amount of interests in securities credited to their accounts. In the event of the insolvency of the Euroclear Operator, Euroclear participants would have a right under Belgian law to the return of the amount and type of interests in securities credited to their accounts with the Euroclear Operator. If the Euroclear Operator did not have a sufficient amount of interests in securities on deposit of a particular type to cover the claims of all Euroclear participants credited with such interests in securities on the Euroclear Operator’s records, all Euroclear participants having an amount of interests in securities of such type credited to their accounts with the Euroclear Operator would have the right under Belgian law to the return of their pro rata share of the amount of interest in securities actually on deposit.

Under Belgian law, the Euroclear Operator is required to pass on the benefits of ownership in any interests in securities on deposit with it, such as dividends, voting rights and other entitlements, to any person credited with such interests in securities on its records.

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Book-Entry Format

Under the book-entry format, the trustee will pay interest or principal payments to Cede & Co., as nominee of DTC. DTC will forward the payment to the direct participants, who will then forward the payment to the indirect participants (including Clearstream, Luxembourg or Euroclear) or to you as the beneficial owner. You may experience some delay in receiving your payments under this system. Neither we, the trustee under the indenture nor any paying agent has any direct responsibility or liability for the payment of principal or interest on the notes to owners of beneficial interests in the notes.

DTC is required to make book-entry transfers on behalf of its direct participants and is required to receive and transmit payments of principal, premium, if any, and interest on the notes. Any direct participant or indirect participant with which you have an account is similarly required to make book-entry transfers and to receive and transmit payments with respect to the notes on your behalf. We and the trustee under the indenture have no responsibility for any aspect of the actions of DTC, Clearstream, Luxembourg or Euroclear or any of their direct or indirect participants. In addition, we and the trustee under the indenture have no responsibility or liability for any aspect of the records kept by DTC, Clearstream, Luxembourg, Euroclear or any of their direct or indirect participants relating to or payments made on account of beneficial ownership interests in the notes or for maintaining, supervising or reviewing any records relating to such beneficial ownership interests. We also do not supervise these systems in any way.

The trustee will not recognize you as a holder under the indenture, and you can only exercise the rights of a holder indirectly through DTC and its direct participants. DTC has advised us that it will only take action regarding a note if one or more of the direct participants to whom the note is credited directs DTC to take such action and only in respect of the portion of the aggregate principal amount of the notes as to which that participant or participants has or have given that direction. DTC can only act on behalf of its direct participants. Your ability to pledge notes to non-direct participants, and to take other actions, may be limited because you will not possess a physical certificate that represents your notes.

Neither DTC nor Cede & Co. (nor any other DTC nominee) will consent or vote with respect to the notes unless authorized by a direct participant in accordance with DTC’s procedures. Under its usual procedures, DTC will mail an omnibus proxy to us as soon as possible after the record date. The omnibus proxy assigns Cede & Co.’s consenting or voting rights to those direct participants to whose accounts the notes are credited on the record date (identified in a listing attached to the omnibus proxy).

Clearstream, Luxembourg or Euroclear will credit payments to the cash accounts of Clearstream, Luxembourg customers or Euroclear participants in accordance with the relevant system’s rules and procedures, to the extent received by its depositary. These payments will be subject to tax reporting in accordance with relevant U.S. tax laws and regulations. Clearstream, Luxembourg or the Euroclear Operator, as the case may be, will take any other action permitted to be taken by a holder under the indenture on behalf of a Clearstream, Luxembourg customer or Euroclear participant only in accordance with its relevant rules and procedures and subject to its depositary’s ability to effect those actions on its behalf through DTC.

DTC, Clearstream, Luxembourg and Euroclear have agreed to the foregoing procedures in order to facilitate transfers of the notes among participants of DTC, Clearstream, Luxembourg and Euroclear. However, they are under no obligation to perform or continue to perform those procedures, and they may discontinue those procedures at any time.

Transfers Within and Among Book-Entry Systems

Transfers between DTC’s direct participants will occur in accordance with DTC rules. Transfers between Clearstream, Luxembourg customers and Euroclear participants will occur in accordance with its applicable rules and operating procedures.

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DTC will effect cross-market transfers between persons holding directly or indirectly through DTC, on the one hand, and directly or indirectly through Clearstream, Luxembourg customers or Euroclear participants, on the other hand, in accordance with DTC rules on behalf of the relevant European international clearing system by its depositary. However, cross-market transactions will require delivery of instructions to the relevant European international clearing system by the counterparty in that system in accordance with its rules and procedures and within its established deadlines (European time). The relevant European international clearing system will, if the transaction meets its settlement requirements, instruct its depositary to effect final settlement on its behalf by delivering or receiving securities in DTC, and making or receiving payment in accordance with normal procedures for same-day funds settlement applicable to DTC. Clearstream, Luxembourg customers and Euroclear participants may not deliver instructions directly to the depositaries.

Because of time-zone differences, credits of securities received in Clearstream, Luxembourg or Euroclear resulting from a transaction with a DTC direct participant will be made during the subsequent securities settlement processing, dated the business day following the DTC settlement date. Those credits or any transactions in those securities settled during that processing will be reported to the relevant Clearstream, Luxembourg customer or Euroclear participant on that business day. Cash received in Clearstream, Luxembourg or Euroclear as a result of sales of securities by or through a Clearstream, Luxembourg customer or a Euroclear participant to a DTC direct participant will be received with value on the DTC settlement date but will be available in the relevant Clearstream, Luxembourg or Euroclear cash account only as of the business day following settlement in DTC.

Although DTC, Clearstream, Luxembourg and Euroclear have agreed to the foregoing procedures in order to facilitate transfers of notes among their respective participants, they are under no obligation to perform or continue to perform such procedures and such procedures may be discontinued at any time.

Same-Day Settlement and Payment

The underwriters will settle the notes in immediately available funds. We will make principal and interest payments on the notes in immediately available funds or the equivalent. Secondary market trading between DTC direct participants will occur in accordance with DTC rules and will be settled in immediately available funds using DTC’s Same-Day Funds Settlement System. Secondary market trading between Clearstream, Luxembourg customers and Euroclear participants will occur in accordance with their respective applicable rules and operating procedures and will be settled using the procedures applicable to conventional eurobonds in immediately available funds. No assurance can be given as to the effect, if any, of settlement in immediately available funds on trading activity (if any) in the notes.

Certificated Notes

Unless and until they are exchanged, in whole or in part, for notes in definitive form in accordance with the terms of the notes, the notes may not be transferred except (1) as a whole by DTC to a nominee of DTC or (2) by a nominee of DTC to DTC or another nominee of DTC or (3) by DTC or any such nominee to a successor of DTC or a nominee of such successor.

We will issue notes to you or your nominees, in fully certificated registered form, rather than to DTC or its nominees, only if:

If any of the three above events occurs, DTC is required to notify all direct participants that notes in fully certificated registered form are available through DTC. DTC will then surrender the global note representing the

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notes along with instructions for re-registration. The trustee will reissue the notes in fully certificated registered form and will recognize the registered holders of the certificated notes as holders under the indenture.

Unless and until we issue the notes in fully certificated registered form, (1) you will not be entitled to receive a certificate representing your interest in the notes; (2) all references in this prospectus supplement or in the accompanying base prospectus to actions by holders will refer to actions taken by the depositary upon instructions from their direct participants; and (3) all references in this prospectus supplement or the accompanying base prospectus to payments and notices to holders will refer to payments and notices to the depositary, as the registered holder of the notes, for distribution to you in accordance with its policies and procedures.

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DESCRIPTION OF DEBT SECURITIES

The following description states the general terms and provisions of our debt securities. The debt securities offered by this prospectus will be issued under one of two separate indentures among us, ONEOK Partners, L.P. and ONEOK Partners Intermediate Limited Partnership (together with ONEOK Partners, L.P., the “Guarantors”), and U.S. Bank National Association, as trustee. We have filed the forms of indenture as exhibits to the registration statement of which this prospectus is a part. The debt securities will be unsecured obligations of ONEOK and will be either senior or subordinated debt. Senior debt will be issued under a senior indenture and subordinated debt will be issued under a subordinated indenture. The senior indenture and the subordinated indenture are sometimes referred to in this prospectus individually as an “Indenture” and collectively as the “Indentures.” Each prospectus supplement that we provide when we offer debt securities will describe the specific terms of the debt securities offered through that prospectus supplement and any general terms outlined in this section that will not apply to those debt securities. Unless otherwise specified in this prospectus, the term “debt securities” includes senior debt securities and subordinated debt securities and the descriptions of the debt securities describe both the senior debt securities and the subordinated debt securities unless otherwise specified in this prospectus or any prospectus supplement.

We have summarized the material terms and provisions of the Indentures in this section. The summary is not complete. We have filed the forms of each of the Indentures as exhibits to the registration statement of which this prospectus forms a part. You should read the applicable form of Indenture for additional information before you buy any debt securities. Each of the Indentures is qualified under the Trust Indenture Act. You should refer to the Trust Indenture Act for provisions that apply to the debt securities. This summary also is subject to and qualified by reference to the description of the particular terms of the debt securities described in the applicable prospectus supplement or supplements and pricing supplement or supplements. Capitalized terms used but not defined in this summary have the meanings specified in the applicable Indenture. In this section, “we,” “us” and “our” refer only to ONEOK, Inc. and not to any of our subsidiaries.

Debt securities issued under either Indenture will be issued as part of a series that will be established pursuant to a supplemental indenture or other authorized corporate action designating the specific terms of the series of debt securities. A prospectus supplement will describe these terms and will include, among other things, the following:

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We may sell the debt securities at a discount (which may be substantial) below their stated principal amount. These discounted debt securities may bear no interest or interest at a rate that at the time of issuance is below market rates. We will describe in the prospectus supplement any material United States federal income tax consequences and other special considerations.

Certain Restrictive Covenants Under Our Senior Indenture

Under the senior indenture, we have agreed to two principal restrictions on our activities for the benefit of holders of the senior debt securities. The restrictive covenants summarized below will apply to a series of senior debt securities (unless waived or amended) as long as any of those senior debt securities are outstanding or, unless the prospectus supplement for the series states otherwise. We have used in this summary description capitalized terms that we have defined below under “—Glossary.” Our Restricted Subsidiaries are those that own or lease a Principal Property.

Other than the restrictions on Liens and Sale/Leaseback transactions under the senior indenture described below, the Indentures and the debt securities do not contain any covenants or other provisions designed to protect holders of any debt securities in the event we participate in a highly leveraged transaction. The Indentures and the debt securities also do not contain provisions that give holders of the debt securities the right to require us to repurchase their securities in the event of change-in-control, recapitalization or similar restructuring or otherwise or upon a decline in our credit rating.

For these purposes, “debt” means obligations for money borrowed, evidenced by notes, bonds, debentures or other similar evidences of indebtedness.

Limitation on Liens

We agree that we will not, and will not permit any Restricted Subsidiary to, create, incur, issue or assume any debt secured by any Lien on any Principal Property, or on shares of stock or debt of any Restricted

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Subsidiary, without making effective provision for the outstanding securities issued under the senior indenture (except as otherwise specified pursuant to an applicable supplemental indenture) to be secured by the Lien equally and ratably with (or prior to) any and all debt and obligations secured or to be secured thereby for so long as such debt is so secured, except that the foregoing restriction will not apply to:

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Limitation on Sale/Leaseback Transactions

We agree that we will not, and will not permit any Restricted Subsidiary to, enter into any Sale and Leaseback Transaction unless:

Glossary

“Attributable Debt” means, as to any particular Sale and Leaseback Transaction under which any Person is at the time liable, at any date as of which the amount thereof is to be determined, the total net amount of rent required to be paid by that Person under the lease during the remaining term thereof (excluding amounts required to be paid on account of maintenance and repairs, services, insurance, taxes, assessments, water rates and similar charges and contingent rents), discounted from the respective due dates thereof at the weighted average of the rates of interest (or yield to maturity, in the case of senior debt securities originally sold at a discount) borne by the debt securities then outstanding under the senior indenture, compounded annually.

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“Consolidated Net Tangible Assets” means the total amount of assets (less applicable reserves and other properly deductible items) that under generally accepted accounting principles, or GAAP, would be included on a consolidated balance sheet of ours and our subsidiaries after deducting therefrom (A) all current liabilities, provided, however, that there will not be deducted billings recorded as revenues deferred pending the outcome of rate proceedings (less applicable income taxes thereon), if and to the extent the obligation to refund the same has not been finally determined, (B) appropriate allowance for minority interests in common stocks of subsidiaries and (C) all goodwill, trade names, trademarks, patents, unamortized debt discount and expense and other like intangibles, which in each case under GAAP would be included on the consolidated balance sheet.

“Funded Indebtedness” as applied to any Person, means all debt of that Person maturing after, or renewable or extendable at that Person’s option beyond, 12 months from the date of determination.

“Lien” means any lien, mortgage, pledge, encumbrance, charge or security interest securing debt; provided, however, that the following types of transactions will not be considered for purposes of this definition to result in a Lien: (1) any acquisition by us or any of our Restricted Subsidiaries of any property or assets subject to any reservation or exception under the terms of which any vendor, lessor or assignor creates, reserves or excepts or has created, reserved or excepted an interest in oil, gas or any other mineral in place or the proceeds thereof, (2) any conveyance or assignment whereby we or any Restricted Subsidiary convey or assign to any Person or Persons an interest in oil, gas or any other mineral in place or the proceeds thereof, (3) any Lien upon any property or assets either owned or leased by us or any Restricted Subsidiary or in which we or any Restricted Subsidiary own an interest that secures for the benefit of the Person or Persons paying the expenses of developing or conducting operations for the recovery, storage, transportation or sale of the mineral resources of the property or assets (or property or assets with which it is unitized) the payment to that Person or Persons of our or a Restricted Subsidiary’s proportionate part of such development or operating expenses or (4) any hedging arrangements entered into in the ordinary course of business, including any obligation to deliver any mineral, commodity or asset in connection therewith.

“Person” means any individual, corporation, partnership, limited liability company, joint venture, association, joint-stock company, trust, unincorporated organization or government or any agency or political subdivision thereof.

“Principal Property” means any property located in the United States, except any property that in the opinion of our board of directors is not of material importance to the total business conducted by us and our consolidated subsidiaries.

“Restricted Securities” means shares of stock or debt of any Restricted Subsidiary.

“Restricted Subsidiary” means any subsidiary that owns or leases Principal Property.

“Sale/Leaseback Transaction” means any arrangement with any Person pursuant to which we or any Restricted Subsidiary lease any Principal Property that has been or is to be sold or transferred by us to that Person, other than (1) a lease for a term, including renewals at the option of the lessee, of not more than three years or classified as an operating lease under GAAP, (2) leases between us and a Restricted Subsidiary or between Restricted Subsidiaries, (3) leases of a Principal Property executed by the time of, or within 12 months after the latest of, the acquisition, the completion of construction or improvement, or the commencement of commercial operation, of the Principal Property and (4) the ground lease for ONEOK Plaza, 100 West Fifth Street, Tulsa, Oklahoma 74103.

Consolidation, Merger and Sale of Assets

The Indentures generally permit a consolidation or merger between us and another entity. They also permit the sale by us of all or substantially all of our assets. We have agreed, unless we inform you otherwise in the

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prospectus supplement, however, that we will consolidate with or merge into any entity or transfer or dispose of all or substantially all of our assets to any entity only if:

Under the senior indenture, if we engage in any of these transactions that result in any Principal Property or shares of stock or debt of any Restricted Subsidiary becoming subject to any Lien and unless we are otherwise able to create that Lien, the senior debt securities (so long as those senior debt securities are entitled to the protection of the “Limitation on Liens” covenant) will be secured to at least the same extent as the debt that would become secured by the Lien as a result of the transaction.

Events of Default

Unless we inform you otherwise in the prospectus supplement, the following are events of default for a series of debt securities:

A default under one series of debt securities will not necessarily be a default under another series. The trustee may withhold notice to the holders of a series of debt securities of any default or event of default (except in any payment on that series of debt securities) if the trustee considers it in the interest of the holders of that series of debt securities to do so.

If an event of default for any series of debt securities occurs and is continuing, the trustee or the holders of at least 25% in principal amount of the outstanding debt securities of the series affected by the default (or, in some cases, 25% in principal amount of all debt securities affected, voting as one class) may require us to pay on an accelerated basis the principal of and all accrued and unpaid interest on those debt securities. The holders of a majority in principal amount of the outstanding debt securities of the series affected by the default (or of all debt securities affected, voting as one class) may in some cases rescind this accelerated payment requirement.

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If an event of default occurs and is continuing, the trustee must use the degree of care and skill of a prudent man in the conduct of his own affairs. The trustee will become obligated to exercise any of its powers under the applicable Indenture at the request of any of the holders of any debt securities only after those holders have offered the trustee indemnity reasonably satisfactory to it.

The holders of a majority in principal amount of debt securities of any series have the right to waive past defaults under the applicable Indenture that relate to that series except for a default in the payment on the debt securities or a provision that can only, under the applicable Indenture, be modified or amended if all holders that are affected consent.

In most cases, holders of a majority in principal amount of the outstanding debt securities of a series (or of all debt securities affected, voting as one class) may direct the time, method and place of:

The Indentures require us to file each year with the trustee a written statement as to our compliance with the covenants contained in the Indentures.

Modification and Waiver

We and each guarantor (if any) may amend or supplement either of the Indentures if the holders of a majority in principal amount of the outstanding debt securities of all series that the amendment or supplement affects (acting as one class) consent to it. Without the consent of the holder of each debt security affected, however, no modification may:

We and each guarantor (if any) may amend or supplement either of the Indentures or waive any provision of such Indenture without the consent of any holders of debt securities in various circumstances, including:

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The holders of a majority in principal amount of the outstanding debt securities under either Indenture may waive our obligations to comply with various covenants, including those relating to:

When we use the term defeasance, we mean discharge from some or all of our obligations under either Indenture. If we deposit with the trustee funds or government securities the maturing principal and interest of which is sufficient to make payments on the debt securities of a series on the dates those payments are due and payable, then, at our option, either of the following will occur:

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If we defease a series of debt securities, the holders of the debt securities of the series affected will not be entitled to the benefits of the applicable Indenture, to provide temporary debt securities, to register the transfer or exchange of debt securities, to replace stolen, lost or mutilated debt securities or to maintain paying agencies and hold money for payment in trust. In the case of covenant defeasance, our obligation to pay principal, premium and interest on the debt securities will also survive.

Unless we inform you otherwise in the prospectus supplement, we will be required to deliver to the trustee an opinion of counsel that the deposit and related defeasance would not cause the holders of the debt securities to recognize income, gain or loss for federal income tax purposes. If we elect legal defeasance, that opinion of counsel must be based upon a ruling from the Internal Revenue Service or a change in law to that effect.

Subordination Provisions for Subordinated Debt Securities

Any subordinated debt securities issued under the subordinated indenture will be subordinate and subject in right of payment to the prior payment in full of all of our Senior Indebtedness. The following provisions will apply to the subordinated debt securities unless otherwise specified in the prospectus supplement:

Subject to any collateral, security, assurance or guarantee provided for the benefit of any series of subordinated debt securities, if any, the payment of principal, any premium and interest on the subordinated debt securities will be subordinated in right of payment to the prior payment in full of all of our Senior Indebtedness. This means that in certain circumstances where we may not be making payments on all of our debt obligations as they become due, the holders of all of our Senior Indebtedness will be entitled to receive payment in full of all amounts that are due or will become due on the Senior Indebtedness before the holders of subordinated debt securities will be entitled to receive any payment or distribution (other than in the form of subordinated securities) on the subordinated debt securities. These circumstances include the following circumstances:

In addition, we are generally not permitted to make payments of principal, any premium or interest on the subordinated debt securities if we default on our obligation to make payments on our Senior Indebtedness and do not cure such default. We are also prohibited from making payments on subordinated debt securities if an event of default (other than a payment default) that permits the holders of senior indebtedness to accelerate the maturity of the Senior Indebtedness occurs and we and the trustee have received a notice of such event of default. However, unless the senior indebtedness has been accelerated because of that event of default, this payment blockage upon notice cannot last more than 179 days.

These subordination provisions mean that if we are insolvent a holder of Senior Indebtedness is likely to ultimately receive out of our assets more than a holder of the same amount of our subordinated debt securities, and a creditor of ours that is owed a specific amount but who owns neither our Senior Indebtedness nor our subordinated debt securities may ultimately receive less than a holder of the same amount of Senior Indebtedness and more than a holder of subordinated debt securities.

The subordinated indenture does not limit the amount of senior indebtedness we are permitted to have and we may in the future incur additional senior indebtedness.

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“Senior Indebtedness” is defined in the subordinated indenture to mean, with respect to us,

“Additional Junior Indebtedness” is defined in the subordinated indenture to mean, without duplication and other than the subordinated debt securities, any indebtedness, liabilities, guarantees or obligations of ours or any of our subsidiaries, under debt securities (or guarantees in respect of debt securities or preferred securities) initially issued after the date of the subordinated indenture to any trust, or a trustee of a trust, partnership or other entity affiliated with us that is, directly or indirectly, a finance subsidiary (as such term is defined in Rule 3a-5 under the Investment Company Act of 1940) or other financing vehicle of ours or any subsidiary of ours in connection with the issuance by that entity of preferred securities or other securities that are issued on a pari passu basis with the subordinated debt securities.

If this prospectus is being delivered in connection with a series of subordinated securities, the accompanying prospectus supplement or the information incorporated by reference will set forth the approximate amount of senior indebtedness outstanding as of a recent date.

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Guarantee

To the extent provided in a prospectus supplement and either a supplemental indenture or a resolution of our board of directors, in each case, relating to a particular series of debt securities, each of our subsidiaries that becomes a guarantor of the debt securities of such series, and any of our subsidiaries that is a successor thereto, will fully, irrevocably, unconditionally and absolutely guarantee the due and punctual payment of the principal of, and premium, if any, and interest on such debt securities, and all other amounts due and payable under the applicable indenture and such debt securities by us to the trustee or the holders of such debt securities, however, such guarantors will not otherwise be subject to the covenants, obligations and duties provided for in the indenture solely in their capacity as guarantors.

Satisfaction and Discharge

The Indentures will cease to be of further effect and will be deemed to have been satisfied and discharged with respect to a particular series of debt securities, when the following conditions have been satisfied:

Governing Law

New York law governs the Indentures and the debt securities.

Trustee

U.S. Bank National Association is trustee under the Indentures. The Indentures contain limitations on the right of the trustee, if it becomes one of our creditors, to obtain payment of claims or to realize payment on property received for those claims, as security or otherwise. The trustee is permitted to engage in other transactions with us in the ordinary course of business. If, however, it acquires any conflicting interest, it must eliminate that conflict or resign.

Form, Exchange, Registration and Transfer

We will issue the debt securities in registered form, without interest coupons. We will not charge a service charge for any registration of transfer or exchange of the debt securities. We may, however, require the payment of any tax or other governmental charge payable for that registration.

Holders may exchange debt securities of any series for other debt securities of the same series, the same total principal amount and the same terms but in different authorized denominations in accordance with the applicable Indenture. Holders may present debt securities for registration of transfer at the office of the security registrar or any transfer agent we designate. The security registrar or transfer agent will effect the transfer or exchange when it is satisfied with the documents of title and identity of the person making the request.

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We have appointed the trustee as security registrar for the debt securities. If a prospectus supplement refers to any transfer agent initially designated by us, we may at any time rescind that designation or approve a change in the location through which any transfer agent acts. We are required to maintain an office or agency for transfers and exchanges in each place of payment. We may at any time designate additional transfer agents for any series of debt securities.

In the case of any redemption, neither the security registrar nor the transfer agent will be required to register the transfer or exchange of any debt security either:

Payment and Paying Agents

Unless we inform you otherwise in a prospectus supplement, payments on the debt securities will be made in U.S. dollars at the office of the trustee. At our option, however, we may make payments by check mailed to the holder’s registered address or, for global debt securities, by wire transfer. Unless we inform you otherwise in a prospectus supplement, we will make interest payments to the person in whose name the debt security is registered at the close of business on the record date for the interest payment.

Unless we inform you otherwise in a prospectus supplement, we have designated the trustee as our paying agent for payments on debt securities issued under the Indentures. We may at any time designate additional paying agents or rescind the designation of any paying agent or approve a change in the office through which any paying agent acts.

Subject to the requirements of any applicable abandoned property laws, the trustee and paying agent will pay to us upon written request any money they are holding for payments on the debt securities that remain unclaimed for two years after the date upon which that payment has become due. After payment to us, holders entitled to the money must look to us for payment. In that case, all liability of the trustee or paying agent with respect to that money will cease.

Book-Entry Debt Securities

We may issue the debt securities of a series in the form of one or more global debt securities that would be deposited with a depositary or its nominee identified in the prospectus supplement. We may issue global debt securities in either temporary or permanent form. We will describe in the prospectus supplement the terms of any depositary arrangement and the rights and limitations of owners of beneficial interests in any global debt security.

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DESCRIPTION OF GUARANTEE OF DEBT SECURITIES

To the extent provided in a prospectus supplement and either an indenture supplement or a resolution of our board of directors, in each case, relating to a particular series of debt securities, each of our subsidiaries that becomes a guarantor of the debt securities of such series, and any of our subsidiaries that is a successor thereto, will fully, irrevocably, unconditionally and absolutely guarantee the due and punctual payment of the principal of, and premium, if any, and interest on such debt securities, and all other amounts due and payable under the applicable indenture and such debt securities by us to the trustee or the holders of such debt securities, and any provisions permitting a release of such guarantee will be included in such prospectus supplement and indenture supplement or resolution, however, such guarantors will not otherwise be subject to the covenants, obligations and duties provided for in the indenture solely in their capacity as guarantors.

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DESCRIPTION OF CAPITAL STOCK

General

We are authorized to issue a total of 1,300,000,000 shares of all classes of capital stock. Of those authorized shares, 1,200,000,000 are shares of common stock, 379,927,619 shares of which were outstanding as of July 3, 2017, and 100,000,000 are shares of preferred stock. Of the authorized preferred stock, there are 20,000,000 shares designated as Convertible Preferred Stock, Series A (none of which was outstanding on July 3, 2017), 30,000,000 shares designated as Convertible Preferred Stock, Series B (none of which was outstanding on July 3, 2017), 1,000,000 shares designated as Series C Participating Preferred Stock (none of which was outstanding on July 3, 2017), and 20,000 shares designated as Series E Non-Voting Perpetual Preferred Stock (all of which were outstanding on July 3, 2017).

The additional shares of our authorized stock available for issuance might be issued at times and under circumstances so as to have a dilutive effect on earnings per share and on the equity ownership of the holders of our common stock. The ability of our board of directors to issue additional shares of stock could enhance the board’s ability to negotiate on behalf of the shareholders in a takeover situation but could also be used by the board to make a change-in-control more difficult, thereby denying shareholders the potential to sell their shares at a premium and entrenching current management.

The following description is a summary of the material provisions of our capital stock and various provisions of our certificate of incorporation and bylaws. This summary is not intended to be complete and is qualified by reference to the provisions of applicable law and our certificate of incorporation and bylaws included as exhibits to the registration statement of which this prospectus is a part.

Common Stock

As of July 3, 2017, there were 13,514 holders of record. The issued and outstanding shares of common stock are validly issued, fully paid and non-assessable. Subject to any preferential rights of any prior ranking class or series of capital stock, including the preferred stock, holders of our common stock are entitled to receive dividends on that stock, payable either in cash, property or shares out of assets legally available for distribution when, as and if authorized and declared by our board of directors and to share ratably in our assets legally available for distribution to our shareholders in the event of liquidation, dissolution or winding-up. Subject to various exceptions, we will not be able to pay any dividend or make any distribution of assets on shares of our common stock until we pay dividends on any shares of preferred stock then outstanding with dividend or distribution rights senior to our common stock.

Holders of our common stock are entitled to one vote per share on all matters voted on by our shareholders, including the election of directors. Our certificate of incorporation does not provide for cumulative voting for the election of directors, which means that holders of more than one-half of the outstanding shares of our voting securities will be able to elect all of the directors then standing for election and holders of the remaining shares will not be able to elect any director.

Our board of directors may make rules and regulations concerning the transfer of shares of our common stock from time to time, in accordance with our bylaws.

Holders of our common stock will have no conversion, sinking fund or redemption rights.

Some provisions of the Oklahoma General Corporation Act, our certificate of incorporation and our bylaws may discriminate against holders of a substantial amount of the shares of our common stock. See “—Oklahoma Law” and “—Certificate of Incorporation and Bylaws.” Similarly, some provisions of our certificate of incorporation and our bylaws may have the effect of delaying, deferring or preventing a change-in-control with respect to an extraordinary corporate transaction, such as a merger, reorganization, tender offer, sale or transfer of substantially all of our assets.

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Preferred Stock

Our board of directors is authorized to issue shares of preferred stock, in one or more series or classes, and to fix for each series or class the preferences, conversion or other rights, voting powers, restrictions, limitations as to dividends, qualifications, or terms or redemption, as are permitted by Oklahoma law and as are stated in the resolution or resolutions adopted by the board providing for the issuance of shares of that series or class.

Our board has authorized series designated as Convertible Preferred Stock, Series A and Convertible Preferred Stock, Series B. Our board has also authorized a series designated as Series C Participating Preferred Stock, which relates to our Second Amended and Restated Rights Agreement. No shares of Series C Participating Preferred Stock were issued, and the Second Amended and Restated Rights Agreement expired February 4, 2013, and was not renewed. Our board has further authorized a series of preferred stock designated as Series E Non-Voting Perpetual Preferred Stock, which is expected to pay quarterly dividends on each share, when, as and if declared by our board, at a rate of 5.5% per year. In April 2017, through a wholly owned subsidiary, we issued and contributed 20,000 shares of Series E Preferred Stock to ONEOK Foundation, Inc. for use in future charitable and nonprofit causes. No other shares of Series E Non-Voting Perpetual Preferred Stock have been issued.

When we offer to sell a particular series of preferred stock, we will describe the specific terms of the securities in a supplement to this prospectus. The prospectus supplement will also indicate whether the terms and provisions described in this prospectus apply to the particular series of preferred stock. The preferred stock will be issued under a certificate of designations relating to each series of preferred stock. The issuance of our preferred stock is also subject to our certificate of incorporation.

Preemptive Rights

No holder of any shares of any class of our stock has any preemptive or preferential right to acquire or subscribe for any unissued shares of any class of stock or any unauthorized securities, convertible into or carrying any right, option or warrant to subscribe for or acquire shares of any class of stock.

Oklahoma Law

Oklahoma Takeover Statute

We are subject to Section 1090.3 of the Oklahoma General Corporation Act. In general, Section 1090.3 prevents an “interested shareholder” from engaging in a “business combination” with an Oklahoma corporation for three years following the date that person became an interested shareholder, unless:

Section 1090.3 defines a “business combination” to include:

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For purposes of the description above and Section 1090.3, the term “corporation” also includes our majority-owned subsidiaries. In addition, Section 1090.3, defines an “interested shareholder” as an entity or person beneficially owning 15% or more of our outstanding voting stock and any entity or person affiliated with or controlling or controlled by that entity or person.

Oklahoma Control Share Provisions

Our certificate of incorporation provides that we are not subject to the control share provisions of the Oklahoma General Corporation Act. With exceptions, these provisions prevent holders of more than 20% of the voting power of the stock of an Oklahoma corporation from voting their shares. If we were to become subject to the control share provisions of the Oklahoma General Corporation Act in the future, this provision may delay the time it takes anyone to gain control of us.

Certificate of Incorporation and Bylaws

Exculpation

Our certificate of incorporation provides that our directors and officers will not be personally liable for monetary damages for any action taken, or any failure to take any action, unless:

Shareholder Action; Special Meeting of Shareholders

Our certificate of incorporation eliminates the ability of our shareholders to act by written consent. Our bylaws provide that special meetings of our shareholders may be called only by a majority of the members of our board of directors.

Advance Notice Requirements for Shareholder Proposals

At any annual meeting of our shareholders, the only business that shall be brought before the meeting is that which is brought:

For business to be properly brought before an annual meeting by a shareholder pursuant to the immediately preceding clause, the shareholder must have given timely notice in writing to our secretary. To be timely as to an annual meeting of shareholders, a shareholder’s notice must be received at our principal executive offices not less than 120 calendar days before the date our proxy statement is released to shareholders in connection with the previous year’s annual meeting; provided however, that if the date of the meeting is changed by more than 30 days from the date of the previous year’s meeting, notice must be received no later than the close of business on the 10th day following the earlier of the day on which notice of the date of the meeting was mailed to shareholders or public disclosure of that date was made. The shareholder notice shall set forth as to each matter the shareholder proposes to bring before the meeting:

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These provisions may impede shareholders’ ability to bring matters before an annual meeting of shareholders.

Higher Vote for Some Business Combinations and Other Actions

Subject to various exceptions, including acquiring 85% of the outstanding shares less shares owned by related persons in a single transaction, a business combination (including, but not limited to, a merger or consolidation, the sale, lease, exchange, mortgage, pledge, transfer or other disposition of our assets in excess of $5,000,000, various issuances and reclassifications of securities and the adoption of a plan or proposal for liquidation or dissolution) with or upon a proposal by a related person, who is a person that is the direct or indirect beneficial owner of more than 10% of the outstanding voting shares of our stock (subject to various exceptions), and any affiliates of that person, shall require, in addition to any approvals required by law, the approval of the business combination by either:

In addition, our certificate of incorporation provides that our bylaws may only be adopted, amended or repealed by a majority of the board of directors or by 80% of our shareholders, voting as a class. Our certificate of incorporation also requires the affirmative vote of 80% of our shareholders to amend, repeal or adopt provisions in our certificate of incorporation relating to, among other things,

Transactions with Interested Parties

Our certificate of incorporation provides that, in the absence of fraud, no contract or other transaction will be affected or invalidated by the fact that any of our directors are in any way interested in or connected with any other party to the contract or transaction or are themselves parties to the contract or transaction, provided that the interest is fully disclosed or otherwise known to our board of directors at the meeting of the board at which the contract or transaction is authorized or confirmed, and provided further that a quorum of disinterested directors is

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present at the meeting of our board of directors authorizing or confirming the contract or transaction and the contract or transaction is approved by a majority of the quorum, and no interested director votes on the contract or transaction. Any contract, transaction or act entered into or taken by us or our board or any committee thereof that is ratified by a majority of a quorum of the shareholders having voting power at any annual meeting, or any special meeting called for that purpose, will be valid and binding as though ratified by all of our shareholders. Any director may vote upon any contract or other transaction between us and any subsidiary corporation without regard to the fact that he is also a director of that subsidiary corporation. No contract or agreement between us and any other corporation or party that owns a majority of our capital stock or any subsidiary of that other corporation shall be made or entered into without the affirmative vote of a majority of the whole board of directors at a regular meeting of the board.