Wall St opens lower; Pfizer weighs on Dow

Wall Street opened lower on Tuesday after Pfizer's tepid forecast and weak U.S. economic data disappointed investors. Dow component Pfizer reported revenue and profit above analysts' estimates, but maintained its previous forecast for the year, sending its shares down 2 percent to $36.66. The stock was the top percentage loser on the Dow and the biggest drag on the S&P 500.