Initial yields on both AAA-rated and non-AAA rated mortgage-backed security (MBS) tranches sold by large issuers are higher than yields on similar tranches sold by small issuers during the market boom years of 2004-2006. Moreover, the prices of MBS sold by large issuers drop more than those sold...

We examine whether rating agencies (Moody's, S&P, and Fitch) reward large issuers of mortgage-backed securities, who bring substantial business, by granting them unduly favorable ratings. The initial yield on both AAA-rated and non-AAA rated tranches sold by large issuers is higher than that on...