A lot of people might not know Zynga’s name, but they sure know its games. “Farmville,” “Mafia Wars,” and “Café World” are some of the biggest titles on Facebook – and continue to draw hundreds of millions of players per month.

That has led to massive growth at the social gaming company. And now SharePost, an exchange for shares of privately held companies, has put a valuation of $5.51 billion on Zynga. If accurate, that would make the company the second largest publisher in the video game industry – ahead of Electronic Arts and far ahead of Take-Two Interactive Software, but still less than industry leader Activision-Blizzard.

Read more at CNBC.com