抵押风险 meaning in English

collateral risk

So it caused considerable surprise on august 23rd when bank of china , one of the country ' s biggest lenders , revealed that it held a $ 9 . 6 billion exposure to securities backed by american subprime mortgages ? albeit most of them highly rated
所以，当中国最大的贷款机构之一，中国银行在8月23日公布其持有96亿美元的美国次级抵押风险债券时，引起震惊?尽管大部分是高收益债券。