The office delinquency rate on commercial mortgage-backed securities (CMBS) reached a new all-time high of 8.89% in July, surpassing the previous peak of 8.83% recorded in September 2012, according to data from Fitch Ratings.

Trepp, a provider of analytics for the commercial real estate industry, reported that the office delinquency rate peaked in January of this year at 12.34%. Since then, the rate has come down to about 11%.

The high delinquency rates signal increasing strain on the sector as higher interest rates, changes in demand and imminent loan maturities pressure commercial real estate.

Fitch found that the overall U.S. CMBS delinquency rate increased 16 basis points to 3.49% in July, up from 3.33% in June of this year. The change was due primarily to the increase in office delinquencies and defaults in mixed-use properties funded with single-asset, single-borrower (SASB) loans.

CMBS refers to loans on commercial properties that have been securitized into bonds and sold to investors on the secondary market. SASB CMBS securitizes one loan on one asset or a pool of assets owned by one borrower. Instead of a tranche of diversified loans, SASBs let investors put their money into a specific property or pool of similar properties.

Fitch reports that new 60-plus-day delinquency volume increased to $2.82 billion in July from $2.09 billion in June. Office delinquencies led the way, accounting for $1.12 billion, or 40% of the total. Mixed-use delinquencies were next, accounting for 26%, or $728 million. Multifamily properties comprised 14% of the total, with retail accounting for 10%.

Resolution volume declined in July to $1.54 billion, down from $1.63 billion in June. Last month’s resolutions included $785 million in loan liquidations, $677 million in loans brought current and $77 million in previously delinquent loans that were removed from Fitch’s index after improving to 30 days delinquent.