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 for-profit educator ITT Educational Services (OTC:ESINQ) sank 10% today after its quarterly update and outlook disappointed Wall Street.

So what: The stock has plummeted in recent months on concerns over enrollment and transparency, and today's preliminary first-quarter results -- total student enrollment fell 6.4% to 57,125 -- coupled with the withdrawal of its full-year guidance only reinforce those worries. In fact, management expects new student enrollments to drop for the first time in four quarters, suggesting that ITT's competitive position is weakening as well. 

Now what: Management withdrew its full-year forecast and said it expects a 4% drop in new student enrollments in the first quarter. "[D]ue to the uncertainties related to the accounting treatment of the PEAKS Trust and the company's guarantee obligations under the PEAKS Program, the company is withdrawing its previously disclosed internal goals for the twelve months ending December 31, 2014, and investors should not rely on those internal goals," wrote ITT in a statement. "The company expects to disclose its revised internal goals for the twelve months ending December 31, 2014 at a later date." When you couple that accounting uncertainty with ITT's worrisome enrollment trends, conservative Fools would probably do well to remain on the sidelines.