Zynga's stock plummeted by almost 40 percent in after-hours trading after the social gaming giant released its second-quarter financial results today. The company's growing revenue reflected its expansion to mobile and other areas, but its large net losses sounded a warning bell to many traders.

　　Zynga's stock almost bought the farm. Zynga reported a net loss of $22.8 million, in contrast to a net profit of $1.4 million in last year's second quarter. Its quarterly revenue came in at $332 million, up 19 percent from the same period of 2011 and up 4 percent from the year's first quarter.

　　The company's second quarter saw a decrease in average daily bookings per average daily user, a financial measurement that reconciles purchasing virtual currency with real currency. It attributed the 10 percent year-over-year drop in bookings from $0.051 in Q2 2011 to $0.046 this year to "new short-term challenges." However, its monthly unique paying users jumped 16 percent from the first quarter, rising from 3.5 million to 4.1 million.

　　Zynga lowered its yearly outlook to account for delays in launching games, declines in existing games related to changes on Facebook that favored new-game discovery, and reduced expectations for Draw Something, which was purchased along with its developer for $200 million in March. Several of Zynga's new and old games remain among the most popular on Facebook, including Zynga Poker, FarmVille, and the puzzle game Bubble Safari.