Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Chinese dot-com darling SINA (Nasdaq: SINA) tanked by 11% this morning on heavy volume, on speculation that it would be the next target of short seller Muddy Waters.

So what: Muddy Waters' short thesis reports are short-term kisses of death. Just ask the last company to be on the receiving end, Focus Media (Nasdaq: FMCN), which saw its shares shed nearly two-thirds of their value at the low when Muddy Waters accused it of fraud recently.

Now what: Since the initial frenzy this morning, shares had even recovered into positive territory before slipping again, after Muddy Waters said it has no report coming on SINA. Investors in Chinese companies have been justifiably jittery amid numerous controversies of late surrounding accounting practices and alleged fraud, so even the hint of foul play sends shareholders fleeing for the exits. SINA's sell-off today is a case of "sell now, ask later" that may give long-term Fools a chance to buy this official Motley Fool Stock Advisor recommendation on the cheap.

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Fool contributor Evan Niu holds no position in any company mentioned. Check out his holdings and a short bio. Motley Fool newsletter services have recommended buying shares of SINA. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.