He started out with 22,203,018 shares and before the latest purchase had 21,888,416 shares, for a total of 314,602 sold shares (or a mere 1.4%). If anything that's a surprisingly little amount of shares sold considering it is the bulk of his net worth. Note that he's a billionaire if you count the equity in Square, his Twitter holdings come out to $645M (counting a cool $54 net gain on his TWTR holdings today!).
And why would he have to sell shares during the ipo? As far as I understand, he should have had virtually no expenses, assuming he (as all founders should) did an 83b election early on.
