* S&P 500, Nasdaq coming off six-day winning streak
* Boeing rallies after results, outlook; AT&T drops
* Biotech shares lower after results, but Gilead gains
* Indexes down: Dow, S&P 500 0.1 pct, Nasdaq 0.5 pct (Updates to open)
By Ryan Vlastelica
NEW YORK, April 23 (Reuters) - U.S. stocks edged lower on Wednesday as strong results from Boeing failed to inspire investors to keep pushing equities higher following six straight days of gains.
Better-than-expected corporate earnings have boosted Wall Street lately, though companies have largely been beating reduced forecasts. According to Thomson Reuters data, profits are seen rising 1.6 percent this quarter, down from the 6.5 percent growth rate estimated at the start of the year.
Boeing Co reported first-quarter revenue that beat expectations and lifted its core earnings forecast to reflect a tax settlement gain, sending shares up 2.7 percent to $131.05. However, this was offset by fellow Dow component AT&T Inc, which fell 3.4 percent to $35.07 a day after its results.
"It's nice to see Boeing rally, but expectations weren't extraordinarily high so it had a low bar to clear," said David Carter, chief investment officer at Lenox Wealth Advisors in New York. "Generally valuations are still supportive for stocks, and reasonable earnings results will support continued gains."
Biotech was again in focus following a trio of key earnings releases. Gilead Sciences Inc late Tuesday posted a sharp profit increase, while Amgen Inc's earnings were below forecasts. Biogen Idec Inc posted strong results and raised its full-year earnings and revenue views.
Shares of Gilead rose 1.7 percent to $74.06 while Amgen dropped 4.3 percent to $114.34. Biogen fell 1.5 percent to $301.50 and the Nasdaq biotechnology index fell 1.2 percent. While results were mixed, they did point to some fundamental strength, easing concerns the group was overvalued.
The Dow Jones industrial average was down 16.89 points, or 0.10 percent, at 16,497.48. The Standard & Poor's 500 Index was down 2.59 points, or 0.14 percent, at 1,876.96. The Nasdaq Composite Index was down 19.58 points, or 0.47 percent, at 4,141.88.
New home sales dropped 14.5 percent in March, tumbling more than expected to an eight-month low.
Among other notable earnings, Procter & Gamble Co's earnings topped analyst forecasts, though shares edged 0.8 percent lower to $79.93. Dow Chemical Co rose 2 percent to $49.90 after reported better-than-expected earnings, helped by improved margins.
With 28 percent of the S&P 500 having reported results through Wednesday morning, 65.2 percent have topped expectations, according to Thomson Reuters data, above the long-term average of 63 percent. On the revenue side, 53.6 percent have exceeded forecasts, below the 61 percent long-term average.
(Editing by Nick Zieminski)