SAN FRANCISCO (MarketWatch) — Zynga Inc. on Friday saw how fickle the stock market can be as the social-media game firm’s shares finished the session with a loss of 5% on the company’s first day of public trading.

Zynga ZNGA, gave up 50 cents a share, or 5%, to close at $9.50 after earlier rising as much as 11.5% following the stock debut. The company sold 100 million shares and raised $1 billion late Thursday after initially setting a price range of $8.50 to $10 a share for its IPO.