(Reuters) - Mattress Firm Group Inc, the mattress selling business of South African retail group Steinhoff, on Monday confidentially filed paperwork with regulators for an initial public offering in the United States. Steinhoff International Holdings N.V. said in August it was evaluating options here, including a public listing, for Mattress Firm, which is the leading specialty mattress retailer in the United States. The Texas-based mattress retailer emerged from bankruptcy here in 2018 two months after it filed for Chapter 11 protection, with access to $525 million in exit financing. It also closed about 660 underperforming stores, Steinhoff said at the time. Steinhoff, whose balance sheet revealed multi-billion euro holes in 2017, has since then been reducing group debt, financing costs and restructuring the debt of some of its units through asset sales and public listings. Mattress Firm sells mattresses both online and through more than 2,500 stores across 49 states in the United States, its website showed as of January 2019.