Shares of online social game maker Zynga plunged 13.3 percent and triggered a trading halt Friday as Facebook's IPO fell flat with investors.
Shares in Zynga, which makes popular games used on Facebook and other platforms, were halted at $7.17, near where they started at the beginning of the week before a strong climb ahead of Facebook's market debut.
Shares of other popular social media companies like Pandora, LinkedIn, and Groupon also tumbled with the Facebook listing: Pandora was off 5.2 percent, LinkedIn 1.2 percent and Groupon 5.6 percent.
Zynga provides about 15 percent of Facebook's revenue, but the company does not hold shares in Facebook.
Nevertheless, its shares fell in parallel with Facebook's, which opened on the Nasdaq Friday at $42 but then quickly fell back to the initial public offering price of $38 as early investors grabbed profits.
At $7.17, Zynga's price was far below its December 2011 IPO price of $10.
Zynga makes and operates the online games FarmVille, Mafia Wars CityVille, Words With Friends and Zynga Poker.