The volume of CMBS loans, against office properties, that will mature by the end of next year is $75.74 billion, according to Trepp.

"That's more than half of the $135 billion of all CMBS loans that were slated to mature this year and next," they wrote. "Meanwhile, $1.08 trillion of the total $5.54 trillion universe of commercial real estate loans come due this year and next."

Terms that can run up to ten years and practices that frequently involve refinancing rather than outright paying the balance mean a significant percentage of mortgages will come due in a given year. This year and 2025 as well, however, could be "fraught with risk," Trepp says. Interest rates are much higher not only during the pandemic but ten years back. "The 10-year Treasury rate, against which most long-term mortgages are benchmarked, is now 4.44%. It ended 2014 at 2.17% and spent just about the entire year in the sub-3% range."