If you are counting, Facebook just bought more shares this quarter; in fact $150 million more of its Class A shares, per the most recent statement of cash flows.
That’s in addition to the $278 million in shares repurchased in the first quarter. Still, Facebook is far away from completing the $6 billion stock repurchase plan announced last fall.
Facebook surprisingly retired all the repurchased Class A shares making it impossible to reissue the shares for future acquisitions. Voting stock, like the Class A shares, is attractive since it can minimize the tax bill due in acquisitions.
Often founders selling out their appreciated stock in an acquisition would rather receive voting stock rather than cash to delay any tax bill.