Clients would pay a fee to share the benefits of that system, he said. Fannie Mae officials also said improved credit-scoring techniques would enable it to lend to people who previously have been deemed too risky and that it would expand lending on manufactured homes and apartments. Chairman and chief executive James A. Johnson said that reverse mortgages, which enable the growing population of elderly Americans to tap the equity in their homes, have "enormous potential" for Fannie Mae. In other market news, specialty finance analyst E. Reilly Tierney, 32, has left Duff & Phelps for Fox-Pitt, Kelton. He will continue to cover subprime auto and mortgage lenders.