Although we don't believe in timing the market or panicking over daily movements, we do like to keep an eye on market changes -- just in case they're material to our investing thesis.

Investors decided to see the bull-market glass as half full on Thursday, with the S&P 500 more than making up for its losses yesterday on positive earnings news from a number of high-profile companies. But several stocks completely missed out on today's gains, as J.C. Penney (JCPN.Q), Overstock.com (BYON -3.98%), and ITT Educational Services (ESINQ) all recorded substantial losses today.

J.C. Penney fell 8%, steepening its downward trajectory from earlier in the week, and hitting levels not seen in more than 20 years. Investors continue to doubt whether the retailer can survive in its current form, even as management has taken steps to deter would-be acquirers or activist investors from taking substantial stakes in the company's stock. The move has valid tax purposes in preserving tax losses from what the IRS would define a change of control; but for investors hoping to score quick turnaround gains, J.C. Penney's poison-pill plan takes away one possible exit strategy.

Overstock.com plunged 22% after reporting its fourth-quarter results. Revenue rose 16% on an eightfold increase in net income. Yet, nearly all of that income came from a one-time bump related to deferred tax assets, without which the online retailer would have just barely grown its overall net income from last year's levels. With the stock having doubled before the announcement, Overstock investors clearly wanted the company's key holiday quarter to be more successful from an operational standpoint.

ITT Educational plummeted 21%, as investors reacted negatively to the for-profit educator's nearly 13% drop in revenue and wider net loss for the fourth quarter. New student enrollment showed promising growth of 4.5%, but total enrollment continued to wane, falling 5.8% from year-ago levels. Given that various state governments expanded their investigations of for-profit educational institutions earlier this week, investors aren't certain about ITT's future prospects.