Unlike previous ACIS policies, which all transfer the credit risk on 30-year mortgages, this one is not linked to a reference pool that already has partial coverage from another risk transfer program called Structured Agency Credit Risk, or STACR. So far, the STACR program, a kind of credit linked note, does not transfer credit risk on 15-year mortgages. Freddie, and sister company Fannie Mae, purchase mortgages from lenders and issue securities backed by the loans that are guaranteed against credit losses. They are tasked by their regulator, the Federal Housing Finance Authority, which obtaining reinsurance on the bulk of this coverage, in order to avoid putting taxpayers on the hook. And 15-year mortgages represent a relatively small percentage of their total business.