Greater Boston has the fourth riskiest loans on office properties among major U.S. metros, with nearly 30 percent falling into a category with elevated risk of default.

Debt researchers Trepp said the risk environment for office buildings is the highest in high-priced coastal markets, which have been affected by layoffs in the tech industry and the hybrid office model.

Only San Francisco, Washington, D.C. and New York had higher risk ratings than Boston according to a Trepp analysis based upon anonymized loan data from large- and mid-sized banks.

The firm ranks 61 percent of San Francisco office loans in the “criticized” category, compared with 32 percent in New York and 29.6 percent in Boston. Since the ratings are based upon year-end data, recent deterioration in capital markets would bring more stress to the troubled property sector, Trepp predicted.

Small and regional banks pursued commercial real estate loans more aggressively in recent years, as an alternative to competing with government-sponsored lenders such as Fannie Mae in the residential market, said Matt Anderson, a managing director at Trepp, during a webinar Friday.

“On the business and consumer side, that’s dominated by the larger banks, so commercial real estate ends up being an area where banks of all sizes can compete,” Anderson said.

An estimated $270 billion in commercial real estate loans are set to mature in 2023, including $79 billion in the office sector.

The Federal Reserve’s series of interest rate hikes has added stress to an office market already reeling from rising vacancy rates since COVID.

In March, the Real Estate Roundtable, whose board is chaired by Suffolk Construction CEO John Fish, asked federal regulators to give lenders more flexibility to work with borrowers, as refinancing requests have been hampered by rising interest rates and uncertain future valuations.

Greater Boston office vacancy rates topped 18 percent for the first time since 2011 in the fourth quarter of 2022, according to JLL research.