The stock sources needed to exercise stock options are: ① the company issues new shares; (2) Repurchase stocks through the retained stock account; ③ Buy stocks from the secondary market. Retained shares refer to the part that an enterprise repurchases issued shares from the market. These shares are no longer held by shareholders, but issued but not circulated. The company will put the repurchased shares into the retained stock account and sell them again in a certain period of time in the future according to the needs of stock options or other long-term incentives.