Impossible to have os of 4+b when the as is only 3b. You should probably re-calibrate your formula you're using.
Keep in mind that much of the volume was the same shares being recycled. Those who bought the 2-300m 2's would have been selling a chunk of them as a quick flip, and then perhaps even buying back.
There has also probably been a billion or so shares dumped in the 1's, many of which would have been for sale, as many would sell half to go to free shares and others would just take the money and run.