Summary Box: Zynga holders to sell stock

STOCK SALE: Zynga shareholders may sell up to $400 million of stock through a public offering, three months after the online game maker went public.

STABILIZES SELLOFFS: The company wants to make sure its stockholders don’t sell a lot of stock all at once when the post-IPO “lock-up” period expires. Early investors typically must wait about six months to sell off parts of their stakes after an initial public offering. Share sales can weigh the company’s stock price on the day that the lock-up expires.

LOCK-UP STAGGERING: Zynga is releasing the selling stockholders from the lock-up, which was set to end on May 28. In exchange, they agreed to longer lock-ups for the rest of their shares.