Wall Street seems to change its mind on the issue every day: Just when will the Federal Reserve cut back the pace of its $85 billion-per-month bond-buying program? Today, markets jittered on fears that Fed tapering will happen sooner than previously thought, perhaps beginning as early as this summer. The S&P 500 Index (SNPINDEX:^GSPC) lost 9 points, or 0.6%, to close at 1,631. But those losses were tame in comparison to the S&P's three biggest decliners.

Dollar General (NYSE:DG) took a big hit, falling 9.2%. The low-price consumer goods retailer was able to grow earnings, but at just a 3% clip. On top of that, the company cut back its own profit estimates for the full fiscal year, which is almost always enough to send a stock tumbling as disappointed investors head to the doors.

Salesforce.com (NYSE:CRM), which earned a spot on this list yesterday after falling more than 3%, dropped 7.9%. Though there wasn't much to be said about the drop yesterday aside from simply observing the online sales company's frothy valuation, today's much steeper decline was driven by its $2.5 billion offer to purchase ExactTarget, a social marketing business. Salesforce shareholders worry the acquisition will make it even harder for the company to return to profitability, at least for the time being.

Even though a surging real estate market has buoyed stock in homebuilders, PulteGroup (NYSE:PHM) fell 3.6% as figures showed big gains in real estate prices in the western U.S., where Pulte doesn't have much exposure. Shares may also have trended lower on concern that any Fed tapering would send interest rates higher, making it less attractive for Americans to borrow money and buy a house.

Fool contributor John Divine has no position in any stocks mentioned. You can follow him on Twitter @divinebizkid and on Motley Fool CAPS @TMFDivine.

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