U.S. stocks fluctuated, after a four-day rally, as weaker-than-forecast results at companies from United Parcel Service Inc. to Kimberly-Clark Corp. offset confidence that central banks will support global growth. UPS slumped 9.6 percent as it said preliminary 2014 earnings were lower than previously forecast, after an over- expanded program to handle a deluge of holiday shipments left its network underutilized on some other days.