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 online media company SINA (Nasdaq: SINA) fell 10% today on concerns that the company's earnings will be worse than expected.

So what: E-Commerce China Dangdang (NYSE: DANG) is driving Chinese Internet stocks lower today after the company reported weak second-quarter earnings. SINA reports earnings Wednesday after the market closes, and there's concern the company will follow in Dangdang's footsteps.

Now what: We'll have to wait another day to hear exactly what SINA has to say, but the market will likely have a strong response for this volatile stock. Short interest has ballooned to more than 10% of SINA's float, and they'll either be proven right or be headed for the hills after earnings. With volatility very high right now, I would wait this out until after earnings when SINA should give us a clue whether its business is impressive or disappointing to investors.

Interested in more info on SINA? Add it to your watchlist.