* Fed reduces asset purchases, upgrades economy assessment
* GDP shows stronger economic growth than expected in Q2
* Dow down 0.3 pct, S&P down 0.1 pct, Nasdaq up 0.3 pct (Updates to late afternoon)
NEW YORK, July 30 (Reuters) - The S&P 500 was near flat on Wednesday after the Federal Reserve gave a rosier assessment of the U.S. economy while reaffirming that it is in no hurry to raise interest rates.
The central bank also, as expected, reduced its monthly asset purchases to $25 billion from $35 billion.
Among the biggest positives were financial shares, with the S&P financial index up 0.4 percent, helping to support the S&P 500. Shares of Wells Fargo gained 1.1 percent to $52.09.
"We got the taper as expected, and the real viewpoint of the committee is they can keep monetary policy accommodative even after we reach our inflation and employment goals," said Art Hogan, chief market strategist at Wunderlich Securities in New York.
The Dow Jones industrial average fell 43.57 points, or 0.26 percent, to 16,868.54, the S&P 500 lost 1.69 points, or 0.09 percent, to 1,968.26, and the Nasdaq Composite added 14.38 points or 0.32 percent, to 4,457.08.
The Dow and S&P 500 both briefly traded higher following the Fed statement.
Earlier Wednesday, government data showed gross domestic product grew at a 4 percent annualized rate in the second quarter, above the 3 percent rate that had been expected and a sharp reversal from the weather-impacted first quarter, when the economy contracted a revised 2.1 percent.
Separately, the ADP National Employment Report showed companies hired 218,000 workers in July, below analysts' projections of 230,000 and less than June's total.
Biotechnology stocks boosted the Nasdaq for a second straight day. The Nasdaq biotech index was up 1 percent after Amgen Inc posted better-than-expected earnings and raised its outlook, sending shares up 5.7 percent to $130.31.
Among other big gainers, Twitter Inc surged 21.5 percent to $48.88, its biggest ever one-day advance, after reporting that monthly active users rose a better-than-expected 24 percent in the second quarter. (Editing by Leslie Adler)