Fitch Ratings affirmed the residential master-servicing rating for Wells Fargo Bank's due to the firm's extensive experience, highly tenured senior management, and "robust servicing oversight program." Analysts said the highest rating in the space also reflects the firm's "ability to effectively oversee and monitor the activities of its primary servicers," as well as the financial condition of its parent company Wells Fargo & Co. (WFC). Wells Fargo has a master-servicing portfolio of mortgage-backed securities of 2.1 million loans with an aggregate value of $476.8 billion as of Aug. 31, which is down from about 2.4 million mortgages worth $546.5 billion a year ago. "Wells Fargo has proactively monitored its primary servicers through preemptive planning for potential events of default, increasing the frequency of its on-site servicer visits, monitoring its back-up servicer readiness and reviewing potential sale solutions," according to Fitch. Wells Fargo has done well managing its master-servicing portfolio amid this challenging market, analysts said. Write to Jason Philyaw.