Shares Set for Mixed Open; Pfizer Reports By: CNBC.com News May 01, 2012 at 06:01 AM EDT US stock index futures pointed to a mixed open on Wall Street on Tuesday in what was likely to be a light trading day with many European and Asian markets closed. Read More >> Related Stocks: BP Plc ADR ConocoPhillips Delta Air Lines Pfizer Time Warner Wal-Mart Stores, Inc.