We incurred approximately $1.7 million and $1.4 million in expenses from related parties during the three months ended September 30, 2021 and 2020, respectively.
General and Administrative Expense
General and administrative expenses were $6.7 million and $30.4 million for three months ended September 30, 2021 and 2020, respectively. The decrease was mainly related to a decrease of $24.4 million stock-based compensation that represented the vesting of a portion of previously granted equity-based awards, and that was recognized in general and administrative expense.
Change in fair value of derivatives
During the three months ended September 30, 2021 and 2020, we recognized a non-cash gain of $58.5 million and a non-cash loss of $139 million, respectively. The gain was primarily due to the decrease of our stock price as of September 30, 2021 ($1.28 per share) compared to June 30, 2021 ($1.47 per share), and the loss was primarily due to the increase of our stock price as of September 30, 2020 ($0.77 per share) compared to June 30, 2020 ($0.34 per share).
Interest Expense
During the three months ended September 30, 2021 and 2020, we recorded interest expense of $1.6 million and $5.5 million, respectively.
Inducement Expense
During the three months ended September 30, 2021, we recorded inducement expense of $0.3 million, which was related to certain warrants exercise.
Nine Months Ended September 30, 2021 and 2020
We recognized a net income of $45.8 million and a net loss of $249.5 million for the nine months ended September 30, 2021 and 2020, respectively. The net income of $45.8 million for the nine months ended September 30, 2021 included a non-cash gain of $93.5 million from change in fair value derivative liabilities.
Research and Development Expense
For the nine months ended September 30, 2021 and 2020, research and development expense was $16.1 million and $24.7 million, respectively. The decrease was mainly related to a decrease of $7 million stock-based compensation that represented the vesting of a portion of previously granted equity-based awards, and that was recognized in research and development expense.
We incurred approximately $5.1 million and $4.2 million in expenses from related parties during the nine months ended September 30, 2021 and 2020, respectively.
General and Administrative Expense
General and administrative expenses were $26.9 million and $39.3 million for nine months ended September 30, 2021 and 2020, respectively. The decrease was mainly related to a decrease of $17.7 million stock-based compensation that represented the vesting of a portion of previously granted equity-based awards, and that was recognized in general and administrative expense, and offset by an increase of approximately $3.4 million related to consulting expenses.
Change in fair value of derivatives
During the nine months ended September 30, 2021 and 2020, we recognized a non-cash gain of $93.5 million and a non-cash loss of $175.2 million, respectively. The gain was primarily due to the decrease of our stock price as of September 30, 2021 ($1.28 per share) compared to December 31, 2020 ($1.53 per share), and the loss was primarily due to the increase of our stock price as of September 30, 2020 ($0.77 per share) compared to December 31, 2019 ($0.21 per share)