Mr Wallace has this week resigned from the position, to which he was appointed in 2005, a spokesman for the bank has announced.
According to an unnamed source cited by Bloomberg, he is leaving for the role of head of mergers and acquisitions in Asia at Citigroup.
Chang Touchen, HSBC's head of investment banking in Southeast Asia, will replace Wallace, said spokeswoman Annie Cheng in a phone interview.
His departure comes soon after that of Michael Smith, who last month departed his role as head of HSBC's head of Asia operations to take up the post of chief executive officer at Australia & New Zealand.
Meanwhile, the firm's London-based global head of capital markets, Daniel Palmer resigned in May.
Mr Wallace will be replaced by Chang Touchen, HSBC spokesperson Annie Chang has told reporters.