Prepayment Models Continue to Improve, But Role of Seller/Servicer Still Being Analyzed The sophisticated prepayment models used by mortgage securities investors and servicing managers have continued to improve as more data have become available, industry experts say. That’s probably a good thing, since most models missed the major prepayment waves that have hit the mortgage industry in recent years. Michael Bykhovsky, president and CEO of Applied Financial Technology, said prepayment models developed from industry data