After the Fed's announcement, the Dow Jones Industrial Average rose to an intraday high of 13,010.0, its first time above the 13,000 level since Jan. 3.
Stocks had rallied earlier on first-quarter economic growth numbers, reinforced by Proctor & Gamble Co. and General Motors Corp. both posting better-than-anticipated results.
"The market continues its retesting of recent highs with Proctor & 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 Dow Jones Industrial Average more recently was up 152.50 points at 12,984.44, with all but three of its 30 components trading higher.
The blue-chip advance was led by GM , recently up 11.7% 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 Proctor & Gamble climbed 3.4% after the consumer-products giant reported earnings that topped forecasts.
Citigroup Inc. led blue-chip declines, its stock off 3.2%.
The S&P 500 gained 11.67 points to 1,402.57, while the Nasdaq Composite climbed 18.91 points to 2,445.01.
Telecommunication services led S&P sector gains, recently up 1.5%, followed by industrials, which was ahead 0.9%. S&P sector declines were fronted by energy, off 0.6%, and information technology, down 0.1%.
Volume on the New York Stock Exchange topped 2.7 billion, while 1.3 billion shares were traded on the Nasdaq, with advancing stocks ahead of those declining more than 2 to 1 on the NYSE and 8 to 5 on the Nasdaq.
On the New York Mercantile Exchange, crude-oil futures reversed course after making early gains, with the contract for June delivery off $1.75 at $113.88 a barrel in a carryover of Tuesday's retreat.
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.
Also, companies in the U.S. private sector added 10,000 jobs in April, according to the ADP employment report. Economists had expected ADP to drop by 55,000 in April
By Kate Gibson