(Bloomberg) -- The world's biggest money managers are staking a claim in the surging market for stock and bond ETFs that strip out currency risk.

Industry giants BlackRock and State Street are rolling out hedged ETFs at an unprecedented clip after smaller rivals lured the bulk of $41 billion of inflows this year. BlackRock started 11 of the funds this month, including ETFs protecting against moves in the Australian dollar and Mexican peso, while State Street opened a euro-focused version in June. Sitting out the year's most popular strategy isn't an option for fund companies, which are increasingly reliant on exchange-traded products to generate income.

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