Jul 15 - Federal Reserve Chairman Ben Bernanke said the U.S. economy is facing "significant downside risks", which was not received well on Wall Street. The Dow dropped 92 points to 10,962. The S&P 500 lost 13 points to 1,214. The Nasdaq rallied 2 points to 2,215. Crude oil had its biggest one-day dollar drop in 17 years. Conway Gittens reports.