US STOCKS-Wall St slips after six-day S&P run; biotechs drop By: Reuters: Company News April 23, 2014 at 14:28 PM EDT * Dow off 0.2 pct; S&P 500 down 0.2 pct; Nasdaq off 0.8 pct (Updates to mid-afternoon, changes byline) Read More >> Related Stocks: AT&T Inc Amgen Biogen Idec Boeing Co Gilead Sciences Illumina Inc Verizon Communications