Home sale prices are surging in working-class neighborhoods of the Bronx — a troubling sign to affordable housing advocates who want to prevent Williamsbridge and Bedford Park from following the path of rapidly gentrifying Brooklyn neighborhoods like Williamsburg and Bedford-Stuyvesant.

The median price of a home in the Bronx’s Kingsbridge Heights and Bedford Park neighborhoods spiked by about 36% over the past two years, the highest increase in the city, according to an annual “Housing Risk Chart” released on Wednesday by the Association for Neighborhood and Housing Development.

The association's tool analyzes factors that lead to displacement, such as eviction filings and home sale prices, for every community district in the city.

Sale prices per square foot also spiked by around 20% or more in the neighborhoods of University Heights, Fordham, Belmont and East Tremont, placing them alongside gentrified Brooklyn areas like Crown Heights, Fort Greene and Greenpoint for the highest rates of increase in the five boroughs, the annual analysis shows. Those Bronx neighborhoods are also among the city's lowest-income areas.

Lucy Block, ANHD’s senior research and data associate, said the spike suggests that real estate speculators are buying low and selling for a hefty profit.

“We see rampant home flipping in some of the neighborhoods where these sale prices are increasing rapidly,” Block said.

Listings on the real estate site StreetEasy show the rising prices. A home on Kingsbridge Terrace that sold for less than $600,000 in 2021 is now listed for $965,000. Another property on Valentine Avenue is on the market for $549,000, more than double what the owners paid in 2009, according to records.

Block said owners who purchase at a higher price often pass the cost on to tenants in the form of higher rents.

“Whenever you see this large increase in residential sale prices over a short period of time, what you're seeing is someone expecting to be able to make a return on a higher price that they're putting into the property,” Block said. “So whether it's a small home or whether it is an entire rental building, they're expecting to have higher income from tenants, and that would be through increasing the rents or lowering the maintenance and the quality of the building.”

Rents are skyrocketing across the city and low-cost apartments are evaporating across the five boroughs, according to the city’s most recent housing survey.

ANHD assessed sale prices per square foot based on Department of Finance data for all 59 of New York City's community districts, but excluded condos, coops and buildings with commercial spaces.

Rolando Guzman, the deputy director of community preservation at St. Nick’s Alliance in northern Brooklyn, said the data captured the pressures that force longtime residents to leave because they can no longer afford housing.

“The report shows what we are seeing on the ground on a regular basis,” Guzman said. “There's a big correlation between these high speculation prices and the pressure that long-term, low-income tenants are facing on a daily basis.”

Tenant and affordable housing groups have previously sounded the alarm on the impact of speculation and surging property prices in neighborhoods like East New York and Bushwick. Some state lawmakers are backing legislation that would institute a “flip tax” on homes bought and quickly resold in specific low-income communities home to people of color.

Councilmember Pierina Sanchez, the housing committee chair, represents many of the Bronx neighborhoods where home prices have soared. She said young people who want to remain in their neighborhoods are being priced out of areas considered “the last bastions of affordability” in the city.

“We're seeing more expensive housing, higher rents, higher pressure and lower housing quality,” Sanchez said. “We’re locked out from the opportunities to own in the neighborhood.”