According to people who had knowledge of the bank's plans, OneWest Bank FSB is looking for a buyer as preparations are underway for its planned initial public offering. The John Paulson and George Soros-backed lender has already been working with Goldman Sachs Group Inc to help them with the search, the sources added.

Initially known as IndyMac Bancorp Inc prior to its failure in 2008, sources said that OneWest had started reaching out to buyers and is expecting to solicit bids from them in the succeeding two months. The sources asked not to be named as the matter and the process is private. The sources added that should OneWest failed to find a buyer in time, it will pursue with the IPO in the second quarter of this year at most.

Filings had shown that the lender has tangible equity worth $3.8 billion at the end of September 2013. According to data compiled by Bloomberg, the potential takeover of OneWest would be the largest for a US bank since ING Groep NV's online lender was acquired by Capital One Financial Corp in 2011 for $9.1 billion.

Since the credit crisis, US regulators had been wary of letting its domestic lenders to grow large.

Last year, people who were familiar with the matter said that OneWest has engaged with US Bancorp, UnionBancal Corp and New York Community Bancorp about a potential exit deal. When the lender was unable to secure a deal last year, the bank decided to prepare to go public, the sources disclosed. The same sources also quoted the lender's owners, who said that they would prefer to exit from their investments in a sale.

When asked by Bloomberg about the exit process, the Pasadena, California-based bank and Goldman Sachs refused to provide comments.

Paulson, Soros and others in a private equity consortium acquired the bank, according to filings.