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 Coach Inc (NYSE:TPR) were knocked down today, falling as much as 11%, and finishing down 9% after the handbag maker issued a dismal forecast for fiscal 2015.

So what: At its investor day meeting, the maker of handbags and other accessories said it would close 70 of its underperforming stores, and that it expected sales to fall in the low double digits in the fiscal year ending June 2015. Same-store sales in North America were projected to fall even more sharply, dropping in the high teens. Coach has seen sales slide in recent quarters as competition from Kate Spade and Michael Kors has taken a bite out of its core mid-range handbag, as the company has focused on other products.   

Now what: Tastes in fashion are fickle, and Coach shareholders are getting a cruel reminder of what happens when shopping habits change. Shares are down close to 40% in the last six months as new CEO Victor Luis's strategy of expanding the product line has not yielded results. The company also seems to have damaged its brand by investing too heavily in outlet stores, which have cheapened the brand image. To counteract the customer flight, management said it will offer twice-a-year purse sales, and is planning to invest more in marketing; but a comparable sales decline near 20% may be hard to come back from. I'd expect shares to fall further before they recover.