NEW YORK ( TheStreet) -- Major U.S. stock averages slumped Wednesday as a spate of weak economic reports prompted investors to question whether the Federal Reserve's stimulus measures are sufficient to prop the U.S. economy. The S&P 500 fell 1.4% to close at 1,608.90 while the Dow Jones Industrial Average also declined 1.4% to 14,960.59. The blue-chip index on Wednesday suffered its third biggest percentage drop this year. The Nasdaq lost 1.3% to 3,401.48. "Nervousness has definitely increased this week and most of the economic data has been a little worrisome," said Ryan Detrick, Cincinnati-based senior technical strategist with Schaeffer's Investment Research. "With the monthly jobs data coming out on Friday, concerns of Fed tapering and a slowing economy has created a sell first, ask questions later mentality." Fastenal ( FAST) was the biggest loser in the S&P after Susquehanna analysts indicated that recent company sales data hinted at a weaker manufacturing economy and business-spending environment. Shares tumbled 6.3% to $47.70. Monsanto ( MON) slipped 3.1% to $98.91 after the fertilizer company's chief technology officer Robb Fraley said sabotage might be the reason behind the unapproved genetically modified wheat discovered in a field in Oregon, adding that testing showed this was an isolated incident. Juniper Networks ( JNPR) was the biggest gaining stock, jumped 6.6% to $18.54 after CEO Kevin Johnson indicated at a technology conference that the networking equipment company's routing performance has been above average in the second quarter. Callaway Golf ( ELY) shed 2.54% to $6.90 after Wedbush analysts slashed their view on the stock to "neutral" and lowered their price target on the stock to $7, explaining that unfavorable weather and "unusually heavy, and perhaps even somewhat irrational," campaigns by rival golf-club maker TaylorMade could hurt sales and margins. The afternoon's Fed Beige Book survey on U.S.-wide economic conditions revealed that economic activity has been increasing at just a "modest to moderate pace." Meanwhile the ADP private payroll employment report showed that private sector employment rose by a disappointing 135,000 in May. Even though it came in above a downwardly revised 113,000 increase for April, the number still missed the average analyst estimate of 165,000 for May. The Census Bureau reported that factory orders rose by a less than expected 1% in April after falling 4.7% in March. Economists were expecting an April gain of 1.5%. Although the composite index from the ISM non-manufacturing survey showed a greater-than-estimated increase to 53.7 in May from 53.1 in April, the employment aspect of the report offset strength in the other components of the report. Economists were expecting a rise to 53.5 in the services sector index for May. In other economic headlines, the Bureau of Labor Statistics reported that first-quarter unit labor costs were revised down to a decline by a 4.3% annual rate after the originally reported increase of 0.5%. The benchmark 10-year Treasury rose 17/32, lowering the yield to 2.093%. Gold futures for August delivery rose $1.30 to $1,398.50 an ounce, while July oil futures ticked up 43 cents to $93.74 a barrel. Follow @atwtseWritten by Andrea Tse in New York >To contact the writer of this article, click here: Andrea Tse.