 Alcoa Corp. AA, 0.36 stock rallied more than 6 in the extended session Wednesday after the aluminum and alumina producer reported second-quarter earnings above Wall Street expectations and said it had a strong first half of the year. Alcoa said it earned 549 million, or 2.95 a share, in the quarter, compared with 309 million, or 1.63 a share, in the year-ago period. 