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 (NYSE: ESI) sank as low as 11% in intraday trading Thursday after its quarterly enrollment figures disappointed investors.

So what: ITT's 20% drop in new-student enrollments was more than twice as bad as Wall Street had expected and also represents the fourth straight quarter of declines. The shares have done well in 2011 despite the uncertainty surrounding for-profit educators, but today's disappointing enrollment number seems to be triggering fresh worries regarding the long-term impact of new industry regulations.

Now what: I'd look into this plunge as a possible entry point. Despite the big enrollment drop, ITT managed to beat Wall Street's top- and bottom-line expectations, and even raised the lower end of its full-year profit forecast. With the stock still trading at a forward P/E discount to industry peers like Apollo Group (Nasdaq: APOL) and DeVry (NYSE: DV), ITT seems like a relatively good bet, as well.

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

Fool contributor Brian Pacampara owns no position in any of the companies mentioned. 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 Fool's disclosure policy always gets a perfect score.