To pay just $770 a month in rent, Mariana Puche Hernandez tolerated the mold growing in the bathroom of her studio apartment, even the sparks that flew when she plugged her phone into an outlet. Then the 11-unit complex on Simmons Avenue in East L.A.

went up for sale and became a prime target for investors looking to renovate apartments and hike the rent beyond what residents could afford. “There was panic,” Puche Hernandez said. Across the nation, the United States is losing thousands of homes affordable to low-income families as individual investors and large companies buy older apartment buildings to renovate and sharply raise rent.

The investments have sparked concerns over gentrification, displacement and homelessness. But affordable housing advocates say there doesn’t have be a choice between renovation and affordable rent. A number of models exist to repair older properties and keep rents low — including nonprofit ownership and certain bond financing programs.

They just need public subsidies and the political will to preserve them or get new ones off the ground. “These units are important to save,” said Matt Alvarez-Nissen, a researcher with the nonprofit California Housing Partnership. That’s because only 16% of low-income California tenants have a home where government policy limits rents based on income, according to the partnership.

The rest, 2.9 million households, live in unsubsidized units subject to the whims of the private market. Rent control la.