Delinquencies tied to commercial mortgage-backed securities experienced five-straight months of declines in 2011, but late payments on office properties are likely to challenge CMBS in 2012, Fitch Ratings said Friday. Office delinquencies in December rose to 6.84%, beating their previous high of 6.64% in July. Meanwhile, CMBS late-pays, overall, declined four-basis points in December to 8.37% from 8.41% a month earlier. Even though office delinquencies are on a upward trend, they maintain one of the lowest delinquency rates. The multifamily segment has the highest delinquency rate of mortgages in CMBS at 14.42%; however, that rate is down from 15.71% in November. The hotel and industrial delinquency rate fell to 12.02% and 10.25%, respectively last month. Write to Kerri Panchuk.