HLT), which is set to be acquired by Blackstone Group ( BX). The change is effective Oct. 24. The New York-based exchange operator also will replace retailer Limited Brands ( LTD) in the S&P 100. Limited Brands, with a market capitalization of $7.9 billion, ranks 100th in the index. The news sent NYSE shares climbing $4.16, or 5%, to $86.80 in after-hours trading. Stocks added to the S&P 500 frequently get a boost because many mutual funds track the index and will buy the stock. For its part, Titanium Metals will be added to the index at a to-be-determined date. The metals producer will replace Bausch & Lomb ( BOL) once the eyecare concern's planned buyout by Warburg Pincus closes. Shares of Dallas-based Titanium Metals were jumping $2.18, or 6.9%, to $33.90 after-hours.