Issuance of expanded-credit MBS is booming but total volume remains relatively small as major investors continue to avoid the sector. Investors such as Blackrock and PIMCO are looking for improvements to representations and warranties, according to industry participants. Eric Kaplan, director of the housing finance program at the Milken Institute’s Center for Financial Markets, said some big investors prefer to acquire expanded-credit loans, such as non-qualified mortgages, as whole loans ...