MannKind Corp. announced Monday that 9 million shares of its common stock were returned by Bank of America according to a stock lending agreement from 2010.

The agreement helped establish hedge positions by investors in the Valencia biotech’s offering of senior convertible notes due in 2015. The shares were collateral for the debt held by note holders.

The lending agreement ended after the full principal amount of notes were no longer outstanding and after MannKind had reconciled all payments and deliveries in regard to the convertible notes, which occurred Aug. 17.

MannKind produces Afrezza, an inhalable insulin. The company worked for years to develop the product, but since its market launch earlier this year sales have come in below analyst expectations.

MannKind shares closed down 7 cents or 1.9 percent to $3.55 on the Nasdaq.