A lot of housing market risk is concentrated in relatively small portions of the country, according to a report from real estate data vendor ATTOM. The company examined counties in home affordability, numbers of underwater mortgages, foreclosures, and unemployment. Rankings were based on a combination of these categories in 590 counties with enough data to analyze in the first quarter of 2024.

"The report shows that California, New Jersey, and Illinois once again had the highest concentrations of the most-at-risk markets in the country, with some of the biggest clusters in the New York City and Chicago areas, as well as inland California. Less-vulnerable markets remained spread mainly throughout the South and Midwest," they wrote. "The 50 counties on the list included six in and around Chicago, five in the New York City metropolitan area, and 14 in areas of California mostly away from the Pacific coast. The rest were scattered around other parts of the country."

Out of the 50 counties most exposed to potential market drops, 34 are found in those three top states, California, New Jersey, and Illinois. There are also large clusters in New York City and Chicago. Less vulnerable markets were spread across the South and Midwest.