Shares of Delta, the second largest carrier behind United Continental (UAL), rose 4.6 percent to $20.80 in after-hours trading.
BMC will be replaced in the index on Tuesday because Bain Capital LLC is expected to complete its acquisition of BMC on or around that day, S&P said.
Delta, which filed for bankruptcy in 2005 and acquired Northwest Airlines in 2008, has improved profits and reduced debt in recent years. It last paid a common stock dividend in 2003, and its last share buyback plan was in 2000.
To cut costs, Delta has been retiring fuel-guzzling planes and acquiring used aircraft, and it bought a Pennsylvania oil refinery last year.
In May, Delta said it planned to return $1 billion to shareholders over the next three years, starting with its first dividend in a decade and a $500 million share buyback program. The initiatives are part of a five-year plan that seeks to generate as much as $5 billion in value for investors.
Airlines, which weathered a tough decade after the September 11, 2001, attacks, have gained more solid financial footing and are now focusing on improving their investment potential.
(Reporting by Nicola Leske; Editing by Bernard Orr and Leslie Adler)