The Bates agency in London will lead the initiative, offering strategic advice on the promotion of HSBC Republic to the super-rich. It will also explore sponsorship opportunities with advertising set to begin early next year.
The appointment, made without a formal pitch, builds on a long-standing relationship between Bates and the world's second-largest bank in its Asian heartland.
HSBC became a significant player in global private banking in 1999 when it paid $9.8bn (£6.3bn) for Republic National Bank of New York.
Its prime targets are international business owners and entrepreneurs with $5m in net assets, $3m in financial assets and $1m in assets under management with HSBC.
Bates is understood to have been selected for the task because of its links with HSBC in the Far East and contacts it maintained after it pitched for HSBC's UK account.
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