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 Medidata Solutions (NASDAQ:MDSO) plummeted 25% on Tuesday after the clinical development software specialist's quarterly results disappointed Wall Street.

So what: The stock had pulled back in recent weeks on worries over slowing growth, and today's first-quarter miss -- adjusted earnings per share of $0.11 on revenue of $76.6 million versus the consensus of $0.16 and $79.6 million -- only reinforces that concern. In fact, Medidata's non-generally accepted accounting principles operating margin fell 620 basis points over the year-ago period to 16.3%, suggesting that its competitive position is becoming increasingly expensive to maintain.

Now what: Medidata remains optimistic about its growth trajectory. "We are seeing great sales momentum, as our pipeline continues to build, giving us confidence that 2014 will be another outstanding year," said Chairman and CEO Tarek Sherif in a press release. "Our industry focus, along with our ability to execute, innovate and make targeted strategic investments, is driving competitive advantage while laying the foundation for sustainable long-term success." Of course, with Medidata shares still trading at a lofty forward P/E of 40, I'd hold out for an even wider margin of safety before betting on it.