Standard & Poor's said Thursday that it plans to add the Chicago Mercantile Exchange ( CME) to its S&P 500 index to replace oil and gas outfit Kerr-McGee ( KMG). Kerr-McGee is set to be acquired by Anadarko Petroleum ( APC) in a $16 billion deal. The S&P's move is effective after the close of trading Aug. 10, which is on or around the date that the Kerr-McGee acquisition is expected to be finalized. Shares of the CME recently jumped $25.23, or 5.5%, to $483.30, in after-hours trading. Shares of companies added to the S&P 500 often rise because fund managers who track the index have to own the stock.