The idea was that they would help advance the mortgage market by buying up mortgages from mortgage originators and therefore allowing them to make more mortgages.

其主旨就是通过,从抵押贷款的原始权益人手中,购买这些债权来促进市场的发展,那些原始权益人就可以去放更多的贷款

耶鲁公开课 - 金融市场课程节选

They would buy mortgages from originators.

他们会从原始权益人手中购买贷款

耶鲁公开课 - 金融市场课程节选