Loans guaranteed by the Federal Housing Administration, the US-owned mortgage insurer, may be involved in more home-purchase transactions than borrowing financed by Fannie Mae and Freddie Mac. FHA lending last quarter may have topped the combined volume of government-supported Fannie Mae and Freddie Mac in a home-lending market that’s still a “government-financed market,” David Stevens, the agency’s head, said today at a conference in New York, citing research by consultant Potomac Partners.