The first quarter of 2015 has just ended, and we won't be hearing from most companies for a few weeks as they prepare all of their financial statements for public viewing. But a select few will be coming out this week, and three of them will likely cause huge moves on the stock market.

That's because all three of these companies -- NeustarW.W. Grainger (NYSE:GWW), and Mattel (NASDAQ:MAT) -- are heavily shorted, with lots of investors betting against their short-term success. When highly shorted companies report earnings, volatility is almost always the result.

But instead of trying to time the market to turn a profit, I suggest that current shareholders prepare for volatility ahead of time. Instead of just focusing on headline numbers, read below to see what's really worth paying attention to.

And if you're really interesting in big events on the stock market this month, don't forget about Apple's release of the iWatch, and all the possible suppliers that could benefit from it.

Photo: W.W. Grainger, Mattel

Brian Stoffel owns shares of Apple. The Motley Fool recommends Apple and Hasbro. The Motley Fool owns shares of Apple and Hasbro. Try any of our Foolish newsletter services free for 30 days. We Fools may not 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.