Sounds like a lot, but it’s not. Pincus still owns 16% of the company, more than any other shareholder.
For some context, Groupon CEO Andrew Mason only sold $10 million back to the company. Though, Groupon founder Eric Lefkofsky sold $257 million back.
Pincus sold his shares in March 2011. We’d guess he was trying to cash out before the IPO lock up period.
See also: Who Gets Rich Off The Zynga IPO?
Here’s a table breaking down insider transactions from the S1. You can see USV has sold $45 million worth of stock:
And here’s who owns what: