New York - Bank of America Corp chief executive Kenneth Lewis on Monday said the acquisition of Merrill Lynch & Co left the banking giant best positioned to weather the financial storm that has engulfed Wall Street and is unlikely to end before 2010.

Lewis said the 50-billion-dollar takeover, which first came under discussion Saturday morning, had been the "strategic opportunity of a lifetime" despite one of the most difficult financial environments in US history.

Diversity in financial assets will be the key to survival, Lewis said, as a major housing slowdown has pummelled the value of mortgage-backed securities in the United States.

The crisis has exposed deep cracks in the financial sector as many banks had been taking on greater debt without maintaining enough capital to meet a sharp downturn.

"The combined company is a much stronger entity and will survive almost anything as a result of the combination," Lewis said, on a day that saw Lehman Brothers Holdings file for bankruptcy and a number of other financial firms in danger of a similar fate.

He spoke to reporters during a broadcast news conference.

Bank of America had reportedly been considering acquiring Lehman Brothers, the fourth-largest US investment bank, during frantic negotiations with government regulators over the weekend.

Lehman was forced into bankruptcy after the US Treasury refused to back its sale with taxpayer funds. The Treasury already bankrolled the sale of another struggling investment giant, Bear Stearns, to JPMorgan Chase in March. The government also took over the operations of mortgage giants Fannie Mae and Freddie Mac last week.

In total, more than 500 billion dollars have been reported in writedowns of mortgage-related assets to date. The Bear Stearns and Fannie-Freddie situations could already cost the taxpayer more than 200 billion dollars.

Lewis and Merrill CEO John Thain, in announcing the merger, said they expected "dramatic" changes in the way financial firms do business in the future, including a simplifying of the kinds of securities and mortgages on offer.

"It's going to be tougher. There are going to be fewer companies and we are going to have to be better at what we do," Lewis said.

Thain described the current climate as the most difficult he had experienced in his 30 years in the financial sector.

"It's definitely a very very difficult time and it's not gonna get better quickly," said Thain, whose role in the new joint venture is unclear. (dpa)