Analyst Upgrades: Zynga Inc, Plug Power Inc, and WebMD Health Corp.

Analysts are weighing in on mobile gaming giant Zynga Inc (NASDAQ:ZNGA), energy issue Plug Power Inc (NASDAQ:PLUG), and health information portal WebMD Health Corp. (NASDAQ:WBMD). Here's a quick roundup of today's bullish brokerage notes on ZNGA, PLUG, and WBMD.

• ZNGA is fresh off a better-than-expected third-quarter earnings report, and news that Chief Financial Officer David Lee is stepping down. These developments are being met with applause on Wall Street, as Benchmark boosted its price target to $3.25 from $3.01 -- though Webush cut its price target to $5.50 from $6, still more than doubling last night's close at $2.45. Still, Zynga Inc is pointed 0.4% lower ahead of the bell, as it tries to rebound from its late-September three-year low of $2.20. The options crowd remains skeptical, based on data from the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX). ZNGA's 50-day put/call volume ratio of 0.31 outranks three-quarters of all similar readings taken in the prior 12 months.

• Ahead of next Monday's quarterly report, PLUG got some love from Wall Street Forensics, which predicted quarterly and full-year revenue above estimates. The upbeat note has the shares 2.1% higher pre-market. Longer term, Plug Power Inc has been on a sharp uptrend since its late-August annual low of $1.55, rallying 85% to trade at $2.87. Option traders are counting on sustained positive momentum, too, based on the stock's 50-day ISE/CBOE/PHLX call/put volume ratio of 24.23 -- just 4 percentage points from an annual high. On the other hand, short sellers may be getting nervous. One-fifth of PLUG's float is sold short, representing 12.6 days' worth of trading, at typical volumes.

• WBMD's earnings and revenue beats (subscription required) prompted Stifel to bump its rating up to "buy," and Cowen to lift its price target to $54. In pre-market trading, the stock is 9% higher after closing at $41.29 yesterday, which should help it break out of a month-long downtrend since hitting a near-term high of $44.56 on Oct. 13. This could put a cramp in the style of option bears, who have been buying to open puts over calls at a feverish pace in recent months. Specifically, WeMD Health Corp.'s 50-day put/call volume ratio of 26.66 sits just 2 percentage points from a 52-week peak.