The share of interest-only loans in fixed-rate securitizations will jump as interest rates rise, according to a new study from Credit Suisse First Boston. The fledgling IO FRM market will also be aided by a flatter yield curve, which will reduce consumer demand for interest-only hybrid ARMs. As more IO loans find their way into mortgage securitizations, those involved in the MBS market will need to carefully review their underlying collateral and prepayment and credit…