Imperva, TESARO, Yelp Upgraded

Analysts are weighing in on cybersecurity stock Imperva Inc (NASDAQ:IMPV), drugmaker TESARO Inc (NASDAQ:TSRO), and consumer review site Yelp Inc (NYSE:YELP). Here's a roundup of today's bullish brokerage notes on IMPV, TSRO, and YELP.

Imperva Eyes Post-Earnings Upside

IMPV blew past earnings expectations last night, in addition to issuing upbeat guidance. The company also announced the sale of its Skyfence product line for roughly $40 million, as well as the acquisition of assets from Camouflage Software. Wall Street is cheering, with no fewer than five analysts raising their price targets -- and Evercore ISI set the highest bar, at $56. Imperva Inc landed Wednesday at $42.90, and is pointed 9% higher pre-market, suggesting it will likely extend its rally off an early November low south of $35. Option bears could get toasted today. IMPV's 10-day put/call volume ratio of 4.55 at the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX) ranks just 2 percentage points from a 12-month peak.

Citigroup Ups Expectations on Takeover Target TESARO

Just a day after notching a record high on buyout rumblings, TSRO saw its price target raised to $232 from $151 at Citigroup -- marking uncharted waters for the shares. This represents 27% upside, relative to yesterday's settlement at $182.68. Meanwhile, TESARO Inc short sellers are likely on pins and needles. Over 22% of the stock's total float is sold short, which would take about two weeks to cover, at typical daily trading volumes.

Yelp Receives Price-Target Hike Ahead of Earnings

YELP, which reports earnings tonight, saw its price target lifted to $52 from $50 at Deutsche Bank. This represents annual-high territory for the stock, which closed yesterday at $41.41 -- just below last week's 12-month peak of $43.41. Bearish options betting has accelerated in the build-up to Yelp Inc's earnings event. The shares sport a 10-day ISE/CBOE/PHLX put/call volume ratio of 1.20, outstripping 95% of all readings from the past year.