US STOCKS-Wall St ends lower after shooting at Canadian parliament
* Indexes turn lower in afternoon trading
* Fall in crude oil weighs on energy shares
* Investors unnerved by shooting in Ottawa
* Indexes down: Dow 0.92 pct, S&P 500 0.73 pct, Nasdaq 0.83 pct
By Yasmeen Abutaleb
NEW YORK, Oct 22 (Reuters) - U.S. stocks erased earlier gains to close lower on Wednesday as a shooting at the Canadian parliament unnerved investors, Boeing and Biogen sold off following results, and energy stocks fell along with oil prices.
Indexes had traded in positive territory for much of the session, putting the S&P 500 on track for a fifth straight day of gains. Earnings initially drove the move higher, with technology and material shares up on the back of strong results.
Market benchmarks began drifting lower after the government reported a surprise increase in crude oil inventories. Energy shares were off 1.7 percent as crude oil fell, settling near $80 per barrel.
Canada's capital was jolted by the fatal shooting of a soldier and an attack on the parliament building in which gunshots were fired outside a room where Prime Minister Stephen Harper was speaking. Toronto stocks fell 1.6 percent, also affected by oil's slide. Continuación...