SVB Financial Group said on Friday it had filed for bankruptcy protection to restructure and find a buyer for its assets. The move comes days after its former subsidiary Silicon Valley Bank was taken over by US regulators.

On March 13, SVB Financial Group said it was planning to explore strategic alternatives for its business.

Shares of big U.S. banks fell more than 1.5 percent in premarket trading. Regional banks, including PacWest Bancorp and First Republic Bank, were down 10 to 20 percent.

The funds and general partner entities of SVB Securities and SVB Capital are not included in the bankruptcy filing, and the group said it plans to continue evaluating alternatives for those businesses and other assets and investments.

Reuters reported on Wednesday that the parent company is exploring seeking bankruptcy protection for the sale of assets.

California regulators shut down Silicon Valley Bank on Friday, making it the biggest bank failure since Washington Mutual collapsed during the 2008 financial crisis.

The collapse paralyzed bank stocks and raised fears of contagion in global markets.

The tech lender was forced to sell a portfolio of Treasury and mortgage-backed securities to Goldman Sachs at a $1.8bn loss after rising yields eroded value. To fill the gap, the company tried to raise $2.25 billion in common and preferred convertible shares, but spooked customers pulled deposits from the bank, leading to $42 billion in outflows in one day.

Silicon Valley Bank said Friday that it had about $2.2 billion in liquidity. The company had $209 billion in assets at the end of last year.