"We're just slip sliding away here, we got everything we expected and it's like two hours after opening Christmas presents -- okay, now what?" said Paul Nolte, director of investments at Hinsdale Associates, of the faded rally after the Fed trimmed short-term interest rates to 2%, and issued what was largely viewed as a neutral statement.
After the Fed's announcement, the Dow Jones Industrial Average rose to an intraday high of 13,010.0, hitting the 13,000 level for the first time since Jan. 3.
But the stock market's enthusiasm quickly waned, with the Dow Jones Industrial Average losing 11.81 points to end at 12,820.13, with 16 of its 30 components losing ground.
Still, the Dow ended with a monthly gain of 4.5%.
Citigroup Inc. led blue-chip declines, its stock off 4%.
Stocks had rallied earlier on first-quarter economic growth numbers, reinforced by Procter & Gamble Co. and General Motors Corp. both posting better-than-anticipated results.
"The market continues its retesting of recent highs with Procter & Gamble and GM numbers leading the way," said Peter Boockvar, equity strategist at Miller Tabak. "Things are weak, but it's an expectations game. Corporate earnings are sluggish, but people are buying stocks on the belief the worst is over."
The blue-chip advance was led by GM , up 9.4% after the automaker reported a first-quarter net loss of $3.25 billion, or $5.74 a share, compared with net income of $62 million a year earlier. Its adjusted loss of 62 cents a share, however, was well ahead of the $1.60-a-share loss analysts were expecting.
Also bolstering the Dow, shares of Procter & Gamble climbed 1.8% after the consumer-products giant reported earnings that topped forecasts.
The S&P 500 shed 5.35 point to 1,385.59, giving it a 4.8% lift in April, while the Nasdaq Composite fell 13.3 points to 2,412.80, a gain of 5.9% from a month ago.
S&P sector declines were fronted by consumer discretionary, off 1.5%, and information technology, down 1.1%. Telecommunication services led S&P sector gains, up 0.5%, followed by energy, up 0.3%.
Volume on the New York Stock Exchange topped 4.4 billion, while nearly 2.2 billion shares were traded on the Nasdaq, with advancing stocks ahead of those declining by 8 to 7 on the NYSE and decliners edging just ahead of advancing issues on the Nasdaq.
Ahead of the opening bell, data showed the U.S. economy grew at an annual rate of 0.6% in the first three months of the year, topping the 0.2% growth expected by economists.
By Kate Gibson