because alt-a loans were not primarily purchased by the gses, they thus became more expensive and much harder to find as a result of the general crisis in markets for mortgage-backed securities. alt-a loans were still available from individual institutions which held them "in portfolio" rather than re-selling them to investors, and as of mid-2008 there was a strong push for the fnma and fhlmc to be permitted to buy more of them. however, the interest rates in this lending category increased substantially between 2006 and 2008 as a result of the shrinking secondary market.