May delinquencies on loans in commercial mortgage-backed securities rose slightly as overall volume of CMBS continued to shrink, according to Fitch Ratings. Delinquencies rose to 8.81% last month from 8.75% in April. The March delinquency rate was 8.74%, which was down two basis points from the prior month and the first drop since October. "The small net delinquency rate increases in each the last three months come in stark contrast to those logged over the previous two years, when the average monthly fluctuation was 0.39%," Fitch analysts said. "Furthermore, the recent driver has been the shrinking of overall CMBS volume outstanding." None of the delinquency rates in all five types of CMBS increased more than five basis points last month. Late payments on multifamily loans rose to 16.8% from about 16.4% while the rate of industrial delinquencies climbed to 10.1% from 9.6% in April. Fitch Managing Director Mary MacNeill said the bifurcation between loans and CMBS transactions is driving the meager volatility in the delinquency rates. The value of delinquent loans in May was $36 billion, down from the high of $37.9 billion in September, according to analysts. "While delinquencies across the CMBS universe appear to be tapering off, pool concentrations and varied underwriting practices continue to expose individual transactions to the potential for future volatility," Fitch said. MacNeill said CMBS deals issued between 1999 and 2001 have high delinquency rates, and transactions from 2006 to 2008 "suffer from performance issues." Loans originated in 2002 to 2004 continue to perform well with delinquency rates ranging of 2.78% to 5.38%. Write to Jason Philyaw.