The U.S. government is considering a new multibillion-dollar aid package for Bank of America Corporation to help it handle losses at Merrill Lynch, which it acquired last year. The new aid package could be modeled after the financial rescue for Citigroup in November. Bank of America could receive another capital infusion from the Treasury and possibly secure government guarantees against losses on bad loans. A new capital injection could come from the Treasury's $700 billion rescue fund, while any money for loan guarantees could come from a mix of government sources. Bank of America already has received $25 billion in capital injections from the Treasury rescue fund. That included $10 billion for Merrill Lynch, which Bank of America bought late in 2008. Shares of both Bank of America and Citigroup plunged more than 20 percent in early trading Thursday.