Ratings agency Moody's Investors Service (MCO) downgraded several batches of residential mortgage-backed securities over the weekend following $2 billion worth of downgrades recorded in the same segment on Friday. The downgrades come at a time when the agency expects more losses associated with subprime loans underlying the securities as home prices plummet and unemployment remains, according to Moody's reports. Subprime mortgage deals worth $143 million issued by Carrington and Soundview were included in the weekend downgrades with Moody's adjusting ratings on 33 tranches from the two firms.  The securities adjusted are backed by first-lien, fixed and adjustable subprime residential mortgages. In addition, the agency downgraded the ratings of 9 tranches of first-lien, fixed and adjustable subprime residential mortgages held by Wells Fargo Home Equity Trust. The agency said, "These actions are a result of deteriorating performance of subprime pools securitized before 2005. Although most of these pools have paid down significantly, the remaining loans are affected by the housing and macroeconomic conditions that remain under duress." Moody's recently modified its ratings criteria as it pertains to pre-2006 pools. Since then, the downgrades are coming fast and heavy. Citing the same circumstances as mentioned above, Moody's also downgraded ratings on 28 tranches of Aegis ABS Trust RMBS totaling $484 million and confirmed the ratings of 2 tranches of subprime loans totaling $10 million. Write to Kerri Panchuk.