Freddie Mac was the top issuer of structured mortgage securities as of the midway point in 2001, despite a somewhat sluggish second quarter in terms of new production. With new mortgage-securitization levels soaring in many categories, issuance of agency-backed CMOs and REMICs actually dropped slightly from the first quarter to the second, falling 1.1 percent to $47.93 billion. As deals priced in June come