There are several reasons a company buys back it's stock:

1. It reduces the shares outstanding and thus improves the EPS even when the revenues don't increase.

2. They can use their own stock as an investment if they believe it is under priced and will improve in the future so they can re-sell it for a profit.

3. They can use the shares as collateral for loans.

4. They can use the shares for stock options for management which helps to obscure the real total income a manager receives.

Which do you think were the reasons why the company bought it's own stock. Personallly, I don't like companies purchasing their stock because they are using funds that should be paid to the stockholders (especially with REITs) who can then choose to buy more of the stock or do other things with the money.