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 Staples (NASDAQ:SPLS) plunged 16% today after the office supply retailer posted disappointing quarterly results and announced a plan to close 225 stores.

So what: The stock has slumped in recent months on concerns over weakening fundamentals, and today's Q4 results -- earnings per share plunged 28% on a top-line decline of 11% -- coupled with the massive store shutdown only reinforce those worries. In fact, Staples' same-store sales during the quarter declined 7% while operating margin contracted 355 basis points, suggesting the company continues to be pressured by intensifying online and discount store competition.

Now what: Management also announced a multiyear cost savings plan, which is expected to generate annual cost savings of about $500 million by the end of 2015. "A year ago, we announced a plan to fundamentally reinvent our company," said Chairman and CEO Ron Sargent. "With nearly half of our sales generated online today, we[']re meeting the changing needs of business customers and taking aggressive action to reduce costs and improve efficiency." More important, with the stock hitting a new 52-week low today and off about 30% over the past three months alone, now might be an opportune time to buy into that turnaround talk.