[BABFSP002.GIF]

Summary Prospectus dated February 1, 2013

Eaton Vance Build America Bond Fund


Class /Ticker     A / EBABX     C / ECBAX     I / EIBAX

This Summary Prospectus is designed to provide investors with key fund information in a clear and concise format. Before you invest, you may want to review the Fund’s Prospectus and Statement of Additional Information, which contain more information about the Fund and its risks. The Fund’s Prospectus and Statement of Additional Information, both dated February 1, 2013, are incorporated by reference into this Summary Prospectus. For free paper or electronic copies of the Fund’s Prospectus, Statement of Additional Information, and other information about the Fund, go to http://www.eatonvance.com/funddocuments, email a request to contact@eatonvance.com, call 1-800-262-1122, or ask any financial advisor, bank, or broker-dealer who offers shares of the Fund. Unless otherwise noted, page number references refer to the current Prospectus for this Fund.

Investment Objectives

The Fund’s primary investment objective is current income and its secondary investment objective is capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.  You may qualify for a reduced sales charge if you invest, or agree to invest over a 13-month period, at least $50,000 in Eaton Vance Funds.  More information about these and other discounts is available from your financial intermediary and in Sales Charges beginning on page 13 of the Fund's Prospectus and page 19 of the Fund’s Statement of Additional Information.  

Shareholder Fees (fees paid directly from your investment)

Class A

Class C

Class I

Maximum Sales Charge (Load) (as a percentage of offering price)

4.75%

None

None

Maximum Deferred Sales Charge (Load) (as a percentage of the lower of net asset value at purchase or redemption)

None

1.00%

None


Annual Fund Operating Expenses (expenses you pay each year as a percentage of your investment)

Class A

Class C

Class I

Management Fees

0.60%

0.60%

0.60%

Distribution and Service (12b-1) Fees

0.25%

1.00%

n/a

Other Expenses

0.29 %

0.29 %

0.29 %

Total Annual Fund Operating Expenses

1.14%

1.89%

0.89%

Expense Reimbursement (1)

(0.19) %

(0.19) %

(0.19) %

Total Annual Fund Operating Expenses After Expense Reimbursement

0.95%

1.70%

0.70%

(1)

The investment adviser and administrator has agreed to reimburse the Fund’s expenses to the extent that Total Annual Fund Operating Expenses exceed 0.95% for Class A shares, 1.70% for Class C shares and 0.70% for Class I shares.  This expense reimbursement will continue through January 31, 2014.  Any amendment to or a termination of this reimbursement would require written approval of the Board of Trustees.  The expense reimbursement relates to ordinary operating expenses only and does not include expenses such as:  brokerage commissions, acquired fund fees and expenses, interest expense, taxes or litigation expenses.  Amounts reimbursed may be recouped by the investment adviser and administrator during the Fund’s current fiscal year to the extent actual expenses are less than the contractual expense cap during such year.

Example.  This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.  The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods.  The Example also assumes that your investment has a 5% return each year and that the operating expenses remain the same.  Although your actual costs may be higher or lower, based on these assumptions your costs would be:

 

Expenses with Redemption

Expenses without Redemption

 

1 Year

3 Years

5 Years

10 Years

1 Year

3 Years

5 Years

10 Years

Class A shares

$

567

$

802

$

1,055

$

1,779

$

567

$

802

$

1,055

$

1,779

Class C shares

$

273

$

576

$

1,004

$

2,196

$

173

$

576

$

1,004

$

2,196

Class I shares

$

72

$

265

$

474

$

1,079

$

72

$

265

$

474

$

1,079




Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” the portfolio).  A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account.  These costs, which are not reflected in Annual Fund Operating Expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund's portfolio turnover was 24% of the average value of its portfolio.

Principal Investment Strategies

Under normal market circumstances, the Fund invests at least 80% of its net assets in taxable municipal obligations issued pursuant to the American Recovery and Reinvestment Act of 2009 (the “Act”) or other legislation providing for the issuance of taxable municipal debt on which the issuer receives federal support (any bonds so issued considered “Build America Bonds”) (the “80% Policy”).  Unlike most other municipal obligations, interest received on Build America Bonds is subject to federal income tax and may be subject to state income tax.  Under the terms of the Act, issuers of “direct pay” Build America Bonds are entitled to receive reimbursement from the U.S. Treasury currently equal to 35% (or 45% in the case of Recovery Zone Economic Development Bonds) of the interest paid on the bonds.  Holders of “tax credit” Build America Bonds receive a federal tax credit currently equal to 35% of the coupon interest received.  The Fund expects to invest primarily in direct pay Build America Bonds and “principal only” strips of tax credit Build America Bonds.  The Fund does not expect to receive (or pass through to shareholders) tax credits as a result of its investments.  Provisions of the Act relevant to the issuance of Build America Bonds expired on December 31, 2010 and, as such, issuance has ceased.  

The Fund may invest up to 20% of its net assets in debt obligations other than Build America Bonds, including (but not limited to) taxable municipal obligations that do not qualify for federal support, U.S. Treasury securities and obligations of the U.S. Government, its agencies and instrumentalities (“Agency Securities”).  At least 65% of net assets normally will be invested in obligations that, at time of purchase, are rated A or better by Moody’s Investors Service, Inc. (“Moody’s”), Standard & Poor’s Ratings Group (“S&P”) or Fitch Ratings (“Fitch”) or, if unrated, are determined by the investment adviser to be of comparable quality. The balance of net assets may be invested in obligations rated BBB/Baa or below and in unrated municipal obligations considered by the investment adviser to be of comparable quality.  The Fund will not invest more than 10% of its net assets in obligations rated below B by Moody’s, S&P or Fitch at the time of investment, or unrated obligations considered by the investment adviser to be of comparable quality.  For purposes of rating restrictions, if securities are rated differently by the rating agencies, the higher rating is used.  The Fund may invest 25% or more of its total assets in certain types of municipal obligations (such as general obligations, revenue bonds and bonds relating to infrastructure financings) and also may concentrate in municipal obligations in a particular economic sector (which may include public utilities, public education facilities, public transportation and public housing).

The Fund may purchase derivative instruments, which derive their value from another instrument, security or index. The Fund may purchase or sell various kinds of financial futures contracts and options thereon to hedge against changes in interest rates or as a substitute for the purchase of portfolio securities. The Fund also may enter into interest rate swaps, forward rate contracts and credit derivatives, which may include credit default swaps, total return swaps or credit options, as well as purchase an instrument that has greater or lesser credit risk than the municipal bonds underlying the instrument.

The investment adviser’s process for selecting obligations for purchase and sale emphasizes the creditworthiness of the issuer or other entity obligated to repay the obligation and the relative value of the obligation in the market.  In evaluating creditworthiness, the investment adviser considers ratings assigned by rating agencies and generally performs additional credit and investment analysis.  Although the investment adviser considers ratings when making investment decisions, with respect to lower rated securities it performs its own credit analysis and does not rely exclusively on the ratings assigned by the rating services.

Principal Risks

Municipal Bond Risk.  The amount of public information available about municipal bonds is generally less than for corporate equities or bonds, meaning that the investment performance of municipal bond investments may be more dependent on the analytical abilities of the investment adviser than stock or corporate bond investments. The secondary market for municipal bonds also tends to be less well-developed and less liquid than many other securities markets, which may limit an owner’s ability to sell its bonds at attractive prices.  The spread between the price at which an obligation can be purchased and the price at which it can be sold may widen during periods of market distress.  Because issuance of Build America Bonds ceased on December 31, 2010, it is difficult to predict the extent to which a market for such bonds will continue, meaning that Build America Bonds may experience greater illiquidity than other municipal obligations.  In addition, municipal obligations can experience downturns in trading activity and the supply of municipal obligations may exceed the demand in the market or demand can exceed supply.



Eaton Vance Build America Bond Fund

2

Summary Prospectus dated February 1, 2013


During such periods, the spread can widen between the price at which an obligation can be purchased and the price at which it can be sold.  Less liquid obligations can become more difficult to value and be subject to erratic price movements.  The increased presence of non-traditional participants or the absence of traditional participants in the municipal markets may lead to greater volatility in the markets.

Debt Market Risk.  Economic and other events (whether real or perceived) can reduce the demand for investments held by the Fund, which may reduce their market prices and cause the value of Fund shares to fall. The frequency and magnitude of such changes cannot be predicted.  Certain securities and other investments held by the Fund can experience downturns in trading activity and, at such times, the supply of such instruments in the market may exceed the demand.  At other times, the demand for such instruments may exceed the supply in the market.  An imbalance in supply and demand in the market may result in valuation uncertainties and greater volatility, less liquidity, wider trading spreads and a lack of price transparency in the market.  No active trading market may exist for certain investments, which may impair the ability of the Fund to sell or to realize the full value of such investments in the event of the need to liquidate such assets. Adverse market conditions may impair the liquidity of some actively traded investments.

Interest Rate Risk.  As interest rates rise, the value of Fund shares is likely to decline.  Conversely, when interest rates decline, the value of Fund shares is likely to rise.  Obligations with longer maturities generally offer higher yields, but involve greater risk because the prices of such obligations are more sensitive to changes in interest rates than obligations with shorter maturities.  In a declining interest rate environment, prepayments of obligations may increase if the issuer has the ability to pre-pay or “call” the obligation.  In such circumstances, the Fund may have to reinvest the prepayment proceeds at lower yields.

Credit Risk.  Changes in economic conditions or other circumstances may reduce the capacity of issuers of fixed income securities to make principal and interest payments and may lead to defaults. Such defaults may reduce the value of Fund shares and income distributions.  The value of a fixed income security also may decline because of real or perceived concerns about the issuer’s ability to make principal and interest payments.  In addition, the credit rating of securities held by the Fund may be lowered if an issuer’s financial condition changes.  Municipal obligations may be insured as to principal and interest payments.  If the claims-paying ability or other rating of the insurer is downgraded by a rating agency, the value of such obligations may be negatively affected.  In the case of an insured bond, the bond’s rating will be deemed to be the higher of the rating assigned to the bond’s issuer or the insurer.

Derivatives Risk.   The use of derivatives can lead to losses because of adverse movements in the price or value of the asset, index, rate or instrument underlying a derivative, due to failure of a counterparty or due to tax or regulatory constraints.  Derivatives may create economic leverage in the Fund, which magnifies the Fund’s exposure to the underlying investment. Derivatives risk may be more significant when derivatives are used to enhance return or as a substitute for a cash investment position, rather than solely to hedge the risk of a position held by the Fund.  When derivatives are used to gain or limit exposure to a particular market or market segment, their performance may not correlate as expected to the performance of such market thereby causing the Fund to fail to achieve its original purpose for using such derivatives. A decision as to whether, when and how to use derivatives involves the exercise of specialized skill and judgment, and a transaction may be unsuccessful in whole or in part because of market behavior or unexpected events.  Derivative instruments may be difficult to value, may be illiquid, and may be subject to wide swings in valuation caused by changes in the value of the underlying instrument.  If a derivative’s counterparty is unable to honor its commitments, the value of Fund shares may decline and the Fund could experience delays in the return of collateral or other assets held by the counterparty.  The loss on derivative transactions may substantially exceed the initial investment.

Risk of Leveraged Transactions.  Certain Fund transactions may give rise to a form of leverage.  Such transactions may include, among others, the use of when-issued, delayed delivery or forward commitment transactions, residual interest bonds, short sales and certain derivative transactions.  The Fund is required to segregate liquid assets or otherwise cover the Fund’s obligation created by a transaction that may give rise to leverage.  The use of leverage may cause the Fund to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations or to meet segregation requirements.  Leverage may cause the Fund to be more volatile than if it had not been leveraged, as certain types of leverage may exaggerate the effect of any increase or decrease in the value of the Fund’s portfolio securities.  The loss on leveraged transactions may substantially exceed the initial investment.

Risk of Lower Rated Investments.  Investments rated below BBB/Baa and comparable unrated securities have speculative characteristics because of the credit risk associated with their issuers.  Changes in economic conditions or other circumstances typically have a greater effect on the ability of issuers of lower rated investments to make principal and interest payments than they do on issuers of higher rated investments.  An economic downturn generally leads to a higher non-payment rate, and a lower rated investment may lose significant value before a default occurs.  Lower rated investments typically are subject to greater price volatility and illiquidity than higher rated investments.

Sector Concentration Risk.  Because the Fund may concentrate its investments in certain sectors or types of obligations, the value of Fund shares may be affected by events that adversely affect that sector or type of obligation and may fluctuate more than that of a less concentrated fund.



Eaton Vance Build America Bond Fund

3

Summary Prospectus dated February 1, 2013


Risk Associated with Limited Issuance.  Under the Act the ability of municipalities to issue Build America Bonds expired on December 31, 2010 and there can be no certainty as to whether future legislation will be enacted that would again permit such issuance.  Since the enactment of the Act, approximately $180 billion in Build America Bonds has been issued by municipalities.  

Given the limited issuance of Build America Bonds, they may not be actively traded.  In addition, illiquidity may negatively affect the value of the bonds.

Risk of U.S. Government-Sponsored Agencies.  Although certain U.S. Government-sponsored agencies (such as the Federal Home Loan Mortgage Corporation and the Federal National Mortgage Association) may be chartered or sponsored by acts of Congress, their securities are neither issued nor guaranteed by the U.S. Treasury.

Risks Associated with Active Management.  The Fund is an actively managed portfolio and its success depends upon the investment skills and analytical abilities of the investment adviser to develop and effectively implement strategies to achieve the Fund’s investment objectives.  Subjective decisions made by the investment adviser may cause the Fund to incur losses or to miss profit opportunities on which it may otherwise have capitalized.

General Fund Investing Risks.  The Fund is not a complete investment program and you may lose money by investing in the Fund.  All investments carry a certain amount of risk and there is no guarantee that the Fund will be able to achieve its investment objectives.  Annual Fund Operating Expenses expressed as a percentage of the Fund’s average daily net assets may change as Fund assets increase and decrease, and Annual Fund Operating Expenses may differ in the future.  Purchase and redemption activities by Fund shareholders may impact the management of the Fund and its ability to achieve its investment objectives.  In addition, the redemption by one or more large shareholders or groups of shareholders of their holdings in the Fund could have an adverse impact on the remaining shareholders in the Fund.  Investors in the Fund should have a long-term investment perspective and be able to tolerate potentially sharp declines in value. An investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency, entity or person.  Mutual funds, investment advisers, other market participants and many securities markets are subject to rules and regulations and the jurisdiction of one or more regulators.  Changes to applicable rules and regulations could have an adverse affect on securities markets and market participants, as well as on the Fund’s ability to execute its investment strategy.

Performance

The following bar chart and table provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and how the Fund’s average annual returns over time compare with those of a broad-based securities market index.  The returns in the bar chart are for Class A shares and do not reflect a sales charge.  If the sales charge was reflected, the returns would be lower.  Past performance (both before and after taxes) is no guarantee of future results.  The Fund’s performance reflects the effects of expense reductions.  Absent these reductions, performance would have been lower.  Updated Fund performance information can be obtained by visiting www.eatonvance.com.

[BABFSP004.GIF]

During the period from December 31, 2009 through December 31, 2012, the highest quarterly total return for Class A was 13.58% for the quarter ended September 30, 2011, and the lowest quarterly return  was -6.31% for the quarter ended December 31, 2010.



Eaton Vance Build America Bond Fund

4

Summary Prospectus dated February 1, 2013



Average Annual Total Return as of December 31, 2012

One Year

Life of Fund

Class A Return Before Taxes

3.44%

10.48%

Class A Return After Taxes on Distributions

1.89%

8.80%

Class A Return After Taxes on Distributions and the Sale of Class A Shares

2.34%

8.01%

Class C Return Before Taxes

6.79%

11.44%

Class I Return Before Taxes

8.87%

12.47%

Barclays Capital U.S. Aggregate Local Authorities Index (reflects no deduction for fees, expenses or taxes)

9.61%

10.10%

These returns reflect the maximum sales charge for Class A (4.75%) and any applicable contingent deferred sales charge (“CDSC”) for Class C.  The Fund commenced operations on November 17, 2009.  Investors cannot invest directly in an Index.

After-tax returns are calculated using the highest historical individual federal income tax rates and do not reflect the impact of state and local taxes.  Actual after-tax returns depend on a shareholder’s tax situation and the actual characterization of distributions, and may differ from those shown.  After-tax returns are not relevant to shareholders who hold shares in tax-deferred accounts or to shares held by non-taxable entities.  After-tax returns for other Classes of shares will vary from the after-tax returns presented for Class A shares.  Return After Taxes on Distributions for a period may be the same as Return Before Taxes for that period because no taxable distributions were made during that period.  Also, Return After Taxes on Distributions and Sale of Fund Shares for a period may be greater than or equal to Return After Taxes on Distributions for the same period because of losses realized on the sale of Fund shares.

Management

Investment Adviser.  Boston Management and Research (“BMR”).

Portfolio Managers

Craig R. Brandon, Vice President of BMR, has managed the Fund since 2009.

Cynthia J. Clemson, Vice President of BMR, has managed the Fund since 2009.

Purchase and Sale of Fund Shares

You may purchase, redeem or exchange Fund shares on any business day, which is any day the New York Stock Exchange is open for business.  You may purchase, redeem or exchange Fund shares either through your financial intermediary or directly from the Fund either by writing to Eaton Vance Funds, P.O. Box 9653, Providence, RI 02940-9653, or by calling 1-800-262-1122.  The minimum initial purchase or exchange into the Fund is $1,000 for each Class (with the exception of Class I) and $250,000 for Class I (waived in certain circumstances).  There is no minimum for subsequent investments.

Tax Information

The Fund’s distributions are expected to be taxed as ordinary income and/or capital gains, unless you are exempt from taxation.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase Fund shares through a broker-dealer or other financial intermediary (such as a bank) (collectively, “financial intermediaries”), the Fund, its principal underwriter and its affiliates may pay the financial intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the financial intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary’s website for more information.

4145-2/13   BABSP

© 2013 Eaton Vance Management




Eaton Vance Build America Bond Fund

5

Summary Prospectus dated February 1, 2013