I don't believe they've bought back that much, because there are rules and restrictions on when and how and how much they can buy. For example, they can't buy above a certain price based on the last price and bid and ask. They can't buy more than 1/4 of the recent daily volume on any given day, although I believe they get one exception to that per week.
Of course, maybe you're talking about all the buyback from the start of the year, in which case, you might be right, but a lot of that buyback was already reported.