It is not mandatory for companies to repurchase their stocks unless they see the need to buy back their shares. There are many reasons why a company may decide to have treasury stocks, some of the reasons are that the company thinks its stocks are undervalued, the company wants to prevent a takeover, or it wants to use the treasury stock to compensate employees. If all these reasons for buying treasury stocks are not important for a company, then it has no need of having treasury stocks.