Well, they created special entities called SIVs and the SIVs would be borrowing money on the commercial paper market to buy subprime loans.

银行建立特殊实体结构投资公司,而结构投资公司,通过在纸货市场借贷,以购入次级债

耶鲁公开课 - 金融市场课程节选

They'd borrow to buy them, so if the value of the subprime loans went down just a little bit the SIV would be in trouble.

结构投资公司还借钱购买次级债,所以只要次级债贬值一点点,他们就麻烦了

耶鲁公开课 - 金融市场课程节选