Australia's Macquarie Bank warned on Wednesday that retail investors in two debt funds face losses of up to 25 percent as fallout from the global credit crunch widened, knocking 10 percent off its shares.

Macquarie, known locally as the millionaire's factory for its big bonuses to staff, is the third Australian institution to flag possible losses as spooked investors have marked down the value of credit assets, with potential losses magnified by borrowings.