NEW YORK ( TheStreet) -- U.S. stocks dropped Friday as concerns the Federal Reserve would scale back its monetary stimulus measures outweighed data that revealed stronger-than-anticipated consumer sentiment. The S&P 500 fell 1.4% to close at 1,630.74 even as the index booked its seventh-consecutive monthly gain, climbing 2.1% in May. The Dow Jones Industrial Average slumped 1.36% to 15,115.57. The blue-chip index lost 1.23% for the week, but gained 1.9% for the month. The Nasdaq dropped 1% to 3,455.91 while the tech-heavy index slipped 0.09% for the week, but jumped 3.8% in May. "Investors are getting ahead of the tape-ering -- trying to be cute here -- and basically I think they're getting worried about something that probably is not something to really worry about just yet," said Sam Stovall, chief equity strategist at S&P Capital IQ. "Maybe we got the sell in May, but it just happened at the end of the month rather than the beginning." The final estimate on the May University of Michigan Consumer Sentiment Index came in at 84.5, above the forecast that it would remain at 83.7. Pall Corp. ( PLL) was the biggest percentage decliner on the S&P plunging 5.1% to $68.20 after the filtration equipment provider cut its full-year earnings estimate after its quarterly net income tumbled 7% and revenue slipped. The Port Washington, N.Y.-based company said its industrial unit suffered softer demand from Asian and European data-storage customers during the quarter in the face of continued economic challenges. The Chicago Institute for Supply Management reported that its business barometer jumped 9.7 to 58.7 in May from April, the highest level since March 2012 and in sharp contrast to April's three and a half year low. All business measures surged this month. This May figure was better than the 50 level expected by economists. Separately, the Bureau of Economic Analysis reported that personal income ticked down less than 0.1% in April after rising 0.3% in March. Economists, on average, were expecting an increase of 0.1% in April. "Overall, the general tone of this report was disappointing as it suggests that households were not in any spending mood at the start of the quarter," Millan Mulraine, U.S. director of research and strategy at TD Securities in New York said in an email. "The recent evidence suggests that this sour mood has reversed in the past month, and only time will tell whether the renewed optimism among U.S. households translates into more buoyant spending." Palo Alto Networks ( PANW) plummeted 11% to $48.52 after the business-technology provider missed quarterly sales estimates and swung to a loss, amid a "tough macroeconomic environment." The company on Thursday evening said despite a tough macroeconomic environment, Palo Alto Networks added over 1,000 new customers for the sixth consecutive quarter. Netflix ( NFLX) added 1.6% to $226.25 after the movie streaming company announced Thursday evening that it will join the NASDAQ-100 index prior to market open on June 6, replacing Perrigo Company ( PRGO ) in the index. Follow @atwtseWritten by Andrea Tse and Joe Deaux in New York >To contact the writer of this article, click here: Andrea Tse.