The past few weeks have been good ones for (Nasdaq: BIDU) investors.

China's leading search engine has bucked the malaise that has plagued many of its country's bellwethers, with its shares soaring 78% higher since last month.

In a testament to Baidu's volatility, the stock is still trading well below its all-time highs set back in November, but it's also sitting pretty as nearly a four-bagger over the past year.

Motion in the ocean
There's a lot of motion in Baidu's stock, but it's also dog-paddling in a sea of catalysts. It's not just about the quarterly earnings, although that will clearly weigh on the stock one way or the other with its Thursday night report.

Baidu has been on the move in many ways, expanding outside its search engine stronghold with recent forays into instant messaging, consumer auctions, online games, and even a bold leap into the mature yet lucrative Japanese search engine market.

Momentum is on Baidu's side heading into this week's report. After a robust clincher to 2007, Baidu has now blown past Wall Street's profit targets in eight of the past 10 quarters since going public. History would point to good odds of Baidu humbling the pros again given its 80% success rate.

There are a couple of reasons to be hopeful. The first is that the company's outlook in February didn't lean on its Japanese efforts to yield material revenue this year. That could prove to be conservative. Baidu is unlikely to make much of a dent in Japan in the near term, but setting up camp there should open both its Chinese and Japanese language search engines to an influx of new international advertisers.

The other catalyst is that if you take Google's (Nasdaq: GOOG) blowout quarterly report last week, and lay it over the bleak comScore (Nasdaq: SCOR) data for Google's domestic clickthrough traffic, one would think that online advertising is booming abroad. Google remains a distant second to Baidu in China, so what's good for Google may be even better for Baidu.

The high price of success
The rub for investors today is that gains in Baidu's stock over the past five weeks have the market's expectations already lapping what Wall Street is braced for come Thursday. Just as we saw shares of Intuitive Surgical (Nasdaq: ISRG) fall last week after handily topping analyst guesstimates -- and even Netflix (Nasdaq: NFLX) got smoked today after simply meeting Mr. Market's forecast -- buoyant share prices need more than just a great report.

The market is already high on Baidu's prospects. Analysts see first-quarter earnings nearly doubling to $0.60 a share. That may seem ambitious, but in the past Baidu has cleared similar obstacles with ease. With China's Internet population on the cusp of lapping the United States to become the world's largest cyberspace-wired nation, it's hard to argue against the company that delivers nearly two-thirds of China's search query results.

However, the hopping shares carry a burden: $0.60 a share won't be good enough. Even squeezing out results just ahead of that profit target may not be enough to prevent a wave of selling. Baidu will have to either obliterate that mark or pull a few rabbits out of its hat.

Baidu is certainly capable of doing exactly that. An upbeat prognosis on anything from Japan to the upcoming Olympic Games to fleshing out details on its entry into Web-based multiplayer games can turn a great report into a stellar one.

Am I concerned that Baidu is vulnerable after running up so quickly? You bet. However, given Baidu's rocky history of taking one step back and then two steps forward, I know that it is ultimately heading in the right direction.

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Longtime Fool contributor Rick Munarriz has been to mainland China just once, but he's longing to brush up on Mandarin and make another go soon. He does not own shares in any companies mentioned in this story except Netflix. Rick is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.