DALLAS, United States — Neiman Marcus Inc., the luxury retailer that filed for an initial public offering in June, is close to an agreement to sell itself to Ares Management LLC and the Canada Pension Plan Investment Board for $6 billion, two people with knowledge of the matter said.

A deal with Neiman’s private-equity owners, TPG Capital, Warburg Pincus LLC and Leonard Green & Partners LP, could be announced as soon as tomorrow, said one of the people. An agreement hasn’t been reached yet and the talks could still fail, said the people, who asked for anonymity because the negotiations are private.

Neiman’s owners have been considering an IPO if they don’t draw a bid that meets their expectations, people familiar with the plan said last month. Neiman runs 41 stores under the same name across the U.S. and two Bergdorf Goodman department stores on New York City’s Fifth Avenue, according to its IPO filing.

TPG and Warburg paid about $5.1 billion for the Dallas- based retailer in 2005. Revenue hasn't returned to the level seen before the 2008 financial crisis at Neiman, as shoppers have been slow to return to stores. Luxury spending in the Americas grew 5 percent on a constant-currency basis in 2012, less than half the 13 percent gain of the previous year, according to Bain & Co. estimates.

Gabrielle de Papp, a spokeswoman for Neiman, didn’t immediately return a phone call and e-mail seeking comment.

The Wall Street Journal reported the negotiations earlier.

By Matthew Monks; Erik Schatzker; Editors: James Callan, Larry Edelman