An SEC filing has revealed that Zynga paid $180 million for OMGPOP, the creator of Draw Something for iOS and Android. This comes just a few days after Zynga officially announced the sale; at the time, most were speculating that the company paid closer to $200 million — thought Peter Kafka from All Things D correctly noted the $180 million price on Twitter. The filing was released in conjunction with Zynga's secondary offering of its stock — the company is putting nearly 43 million shares back on the market. CEO Mark Pincus is personally selling 16.5 million of his shares, which will reduce his voting share from 36.5 percent to 35.9 percent. While this sale comes in at some $20 million less than initially speculated, we'll have to wait and see if Zynga gets a good return on that large investment.