Stocks to watch Tuesday: Pfizer, Comcast, Westlake

Comcast (NASDAQ:CMCSK) Mastercard (NYSE:MA) Westlake Chemical Corp. (NYSE:WLK) MetroPCS Communications Inc. (NYSE:PCS) Also Tuesday, McKesson Corp. (NYSE:MCK) Tenet Healthcare Corp. (NYSE:THC) Archer Daniels Midland Co. (NYSE:ADM) Avon Products Inc....