Senior executives close to the banks informed Campaign Asia-Pacific about the results of the two ptiches, which were called in June.
Leo Burnett was the long-term incumbent on the Hang Seng Bank creative account, while DDB previously worked with Bank of China on a project basis. DDB did not participate in the Bank of China pitch.
A source said the winning agencies had been notified, but added that contracts have not yet been "cast in stone".
DDB declined to comment.