NEW YORK (AP) -- Standard & Poor's said Thursday it will add miner Freeport-McMoRan Copper & Gold Inc. to its S&P 100 index to replace Schering-Plough Corp., after the drugmaker merges with Merck & Co. in a deal expected to be completed soon.

Priceline.com Inc. will replace Schering-Plough in the S&P 500, and equity index product provider MSCI Inc. will replace the online travel discounter in the S&P MidCap 400, S&P said in a statement.

The date of the changes were not announced.

Shares of Priceline jumped 4.6 percent in aftermarket trading to $170.05, while shares of MSCI climbed $2.27, or nearly 8 percent, to $31.50. Freeport-McMoRan shares edged up $1.18 to $79.35 after-hours.

Stocks often rise after they are added to major indexes as they are bought by managers of investment funds that mirror the indexes.