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 physician services provider MEDNAX (NYSE: MD) tested positive for declines today, dropping as much as 10% in intraday trading before recovering some ground.

So what: MEDNAX announced fourth-quarter results today and investors were underwhelmed. Profit per share of $1.12 for the quarter met analyst estimates, but revenue, which was up 10.6% from the year-ago quarter, was well-shy of expectations. One a same-unit sales basis, the company saw patient volume growth of 1.6%, but a shift toward more services being reimbursed at lower rates by the government left total same-unit sales growth at just 0.2%.

Now what: Of course, disappointment over fourth-quarter results probably had a lesser impact on MEDNAX shares today than the company's outlook for the first quarter. Guidance for first-quarter earnings per share was set at $0.88 to $0.93, easily short of the $0.96 Wall Street was looking for. However, investors can't be too dismayed with the stock; since the beginning of August it's been on a furious tear that has it up 34% even after today's drop.

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