Tsuneo Wakai, chairman of Bank of Tokyo-Mitsubishi, said his bank would use its position to help ensure that the excesses of Japan's late Eighties "bubble economy", which saddled banks with huge debts from over-aggressive property lending, were not repeated.
"The banking industry must change its behaviour, such as lending heavily to a single sector or doing things just because other members of the industry have done them," Mr Wakai said.
He added: "We must establish procedures that will prevent a recurrence of what happened in the bubble economy."
The merger of Mitsubishi Bank and Bank of Tokyo, formally completed on Monday, created the world's biggest bank in terms of its assets, which total 77,500bn (pounds 474bn).
Industry analysts said the merger could put additional pressure on other Japanese banks to seek marriages as deregulation and bad debt problems threaten a shake-out.
The merger also coincided with two other big mergers in the US. Chase Manhattan Corp merged on Sunday with Chemical Banking Corp to create the largest US bank, with assets of $305bn (pounds 200bn), and yesterday saw San Francisco-based Wells Fargo and Co team up with First Interstate Bancorp.
Bank of Tokyo-Mitsubishi, which combines Mitsubishi's powerful domestic network and Bank of Tokyo's strong international operations, will tower over most domestic rivals in size and quality, analysts said.
Before the merger, Mitsubishi and Bank of Tokyo were separately rated single A plus.
The new bank said it would start operations with about 21,000 employees, 366 domestic branches including headquarters and other outlets, and 83 overseas branches and representative offices.
Cutting staff and redundant operations is expected to be one key to boosting the bank's profitability and deriving benefits from the merger.
Last month, bank officials said they would consider cutting some 2,000 jobs over three years.Reuse content