Zynga's shares are now trading under $8.80, which means CEO Mark Pincus' share of the company is now worth less than $1 billion.
Pincus owns around 111 million shares of the company. When it went public, Pincus' share was worth $1.06 billion. It's now worth $979 million.
The next largest investor is Bing Gordon, who along with Kleiner Perkins Caufield & Byers owns 65 million shares.