The Canadian Imperial Bank of Commerce said on Monday that it would issue 2.75 billion Canadian dollars in stock at substantially discounted prices as part of an effort to ease investor anxiety about its subprime mortgage exposure.

The bank, based in Toronto, has by far the biggest exposure of any Canadian bank to troubled American mortgage debt, about $9.8 billion. It also confirmed that it would take a $462 million write-down on the unhedged part of that debt as well as a $2 billion write-off for subprime exposure insured by the troubled underwriter ACA Financial Guaranty Corporation.

The write-downs, which are deductible, will have an after-tax drag of $1.6 billion, the bank said, adding that further write-downs may be needed.