A record $465.3 billion of adjustable-rate mortgages were securitized during last year’s booming mortgage market, a hefty 61 percent increase from the total for 2002, according to a new analysis by Inside MBS & ABS. While records fell all over the mortgage and MBS markets in 2003, the big gain in ARM securitization is particularly remarkable because consumers had the opportunity to lock in fixed-rate mortgages