The Dow’s winning streak still alive -- just barely.
The Dow Jones industrial average, which had not recorded a losing month since September, dipped about 14 points on Monday, finishing the month up about 1 point.
The S&P 500 slid about 5 points, recording its first monthly retreat since November. The Nasdaq dipped about 22 points.
The markets fell after data hinted the U.S. economy may be slowing and Spain's fall into recession underscored nagging stresses in the euro zone.
But despite Monday's declines the picture was not overwhelmingly negative. Last week saw four days of back-to-back gains that helped the index erase steeper losses for the month. The S&P closed above 1,400 for the first time in three weeks on Friday, largely helped by better-than-expected corporate earnings.
Still, a string of economic data is starting to suggest the economy may slow in the summer months and is causing the market to stall just shy of four-year highs. A gauge showing a much sharper-than-expected decline in Midwestern business activity in April was the latest such measure to point to a slowdown.
"On the trading front, in equities, we stepped back to neutral several weeks ago," said Goldman Sachs in a research note. "Our general view is that the U.S. seems to be slowing -- though how much and for how long is an open question -- while equity market domestic growth views remain elevated."
Spain's economy sank into recession in the first quarter as deep government spending cuts to reduce a massive deficit and troubles in the banking sector likely delayed any return to growth. Though expected the news highlighted the serious headwinds the world economy faces.
Banks were among the top decliners on Wall Street after Standard & Poor's cut the credit ratings of 11 Spanish banks on Monday, following its downgrade of Spain last week.
The S&P 500 financial sector index fell 0.7 percent while Bank of America Corp dropped 1.2 percent to $8.15. Shares of Spanish bank Santander traded in New York fell 3.1 percent to $6.27 and are down 17 percent this year.
The S&P 500 was down about 1 percent in April. Early in the month, worries over Europe and the U.S. economy sent the index down over 4 percent for the month.
In earnings news, Humana Inc declined 9 percent to $79.98 after the company, one of the largest providers of Medicare insurance for the elderly, posted a 21 percent drop in profit. The Morgan Stanley healthcare payor index declined 2.1 percent.
Exchange operator NYSE Euronext reported its quarterly profit fell by almost one-third due to a difficult trading environment and costs from its failed merger with Deutsche Boerse. Its shares were off 6.2 percent to $25.39.
According to Thomson Reuters data through Monday morning, of the 297 S&P 500 companies that have reported quarterly results so far, 72 percent topped estimates. A strong earnings season helped lift the benchmark S&P index to its best week since mid-March on Friday.
On the positive side, shares of Sunoco Inc jumped 19.7 percent to $48.95 after pipeline operator Energy Transfer Partners LP said it would buy the company for $5.35 billion in stock and cash.
Barnes & Noble Inc surged about 62 percent to $22.16 after Microsoft Corp agreed to invest $300 million in the bookseller's digital and college operations. The deal values the Nook and textbook businesses at $1.7 billion.
Reuters contributed to this report.