(Reuters) - Shares of Zynga Inc slumped 42 percent to their lowest ever on Thursday, after fading fortunes of hit games such as "FarmVille" on Facebook forced the company to slash its outlook.
The slide wiped $1.5 billion off Zynga's value, taking it to just $2.2 billion -- a far cry from the Internet gaming firm's IPO launch value of nearly $9 billion last December.
A slew of analysts cut their ratings and price targets for Zynga after it reported lower-than-expected quarterly results on Wednesday and forecast a much smaller 2012 profit.
Zynga has been hit by user fatigue for some of its long-running games and a shift in the way Facebook Inc's social platform promotes games.
"The biggest factor impacting current performance appears to be the way Facebook is surfacing gaming content on its platform," JP Morgan's Doug Anmuth wrote in a note to clients.
Surfacing refers to how a website displays content.
Facebook recently tweaked the way users find games in its app center -- giving prominence to newer titles and pushing down older games -- making it difficult for users to find some of Zynga's most popular titles.
"FarmVille", which contributed 29 percent of Zynga's second-quarter revenues, slid to 20 million users this month from a high of about 80 million in March, according to Appdata.com, a Facebook tracking service.
Zynga's weak outlook spooked Facebook investors who are waiting for the social networking company to report results for the first time on Thursday.
Zynga, which relies on Facebook for more than 90 percent of its revenue, was the most heavily traded stock on the Nasdaq on Thursday morning and the biggest percentage loser.
J.P. Morgan Securities, Citi Investment Research, Lazard Capital Markets, Stifel Nicolaus, Morgan Stanley and Goldman Sachs downgraded Zynga's stock to "neutral," or equivalent ratings.
At least six other brokerages slashed their price targets on the stock to as low as $3.00.
On top of the drop in users for core money-making games such as "FarmVille" and "Hidden Chronicles", a new game Zynga bought in March, "Draw Something", has also not lived up to its hopes.
Prospects for games on Facebook have deteriorated as users tire of games where players manage farms, zoos and other environments, analysts say.
A shift by users to accessing Facebook through mobiles, which have less space for advertising, adds to the pressure.
"As Zynga looks to grow its footprint in the mobile category, the traditional Facebook business was expected to act as a solid foundation, but is instead showing incremental weakness," said Piper Jaffray analysts.
The woes highlight the fading fortunes of consumer Internet stocks that were once heavily bet on. This month, an investment analyst said Facebook had shed users in both the United States and Europe over the past six months.
(Reporting by Rachel Chitra and Sayantani Ghosh; Editing by Tenzin Pema and Rodney Joyce)