A view of the Casper mattresses during Casper's LA celebration at Blind Dragon on July 9, 2015 in West Hollywood, California.

Casper Sleep Inc, the U.S. online mattress retailer whose investors include actor Leonardo DiCaprio and rapper 50 Cent, is seeking to hire underwriters for an initial public offering (IPO), according to people familiar with the matter.

Casper's IPO comes as the company has been expanding into brick-and-mortar retail, transitioning from temporary to permanent stores. It is betting that its popularity with urban millennials will ensure it does not share the same fate as Mattress Firm Inc, the largest U.S. brick-and-mortar mattress retailer that filed for bankruptcy protection last year.

New York-based Casper, which was valued at $920 million in its latest private fundraising round in 2017, is planning to interview investment banks in April to hire underwriters for its IPO, the sources said, asking not to be identified because the matter is confidential.

Casper declined to comment.

Launched in 2014, Casper is one of a string of online mattress retailers, such as Purple, Nectar Sleep and Tuft & Needle, that have squeezed the industry's old players. Mattress Firm emerged from bankruptcy and closed about 660 underperforming stores.

Having risen to prominence selling its mattresses online and shipping them out in boxes, Casper opened its first permanent store in New York in 2018 with plans to open 200 stores in the coming years.

Led by its co-founder Philip Krim, Casper made its name by selling one "universally comfortable" type of memory-foam mattress, as opposed to offering different firmness options and designs. It now sells three different types of mattresses.

Casper's investors include retailer Target Corp and investment firms Lerer Hippeau Ventures, IVP and NEA.

If it goes ahead with the IPO plans, Casper would be the latest high-profile consumer company to debut in the stock market this year.

Jeans maker Levi Strauss & Co completed its IPO last week while ride-hailing start-up Lyft is set to begin trading on the Nasdaq on Friday.

Uber Technologies Inc is planning to kick off its initial public offering in April, Reuters has reported.