Zynga has seen its shares fall 10 per cent following a damning analyst report.
Doug Kreutz of Cowen and Co said Facebook games were 'in an accelerating user tail spin'.
NASDAQ stock exchange has temporarily stopped short selling of stock.
The CityVille developer closed today's trading at $4.98, down from $5.55 the day before. It's a far cry from its high of $15.91 in February.