A version of this article first appeared in CNBC's Inside Wealth newsletter with Robert Frank, a weekly guide to the high-net-worth investor and consumer. Sign up to receive future editions, straight to your inbox.

Private investment firms of ultra-rich families could inadvertently get caught in the crosshairs of President Donald Trump's proposed ban on "large institutional investors" buying more single-family homes. While Trump's announcement took aim at Wall Street landlords, and particularly private equity giants like Blackstone, Haynes Boone partner Vicki Odette told Inside Wealth that family offices aren't necessarily out of the woods.

Three-quarters of family offices in North America invest in real estate, with an average allocation of 18%, according to a survey issued by Campden Wealth and RBC Wealth Management last year. Residential properties made up just under a third of the average family office's real estate holdings, per the same report.

The consequences of Trump's proposal hinge on how it would define a large institutional investor, which has yet to be revealed. According to Odette, in recent years, Congress and government agencies have focused on the number of homes owned rather than the investor's total assets or investment strategy.

A 2024 report by the Government Accountability Office about institutional investors focused on those who own more than 1,000 properties of four units or less. The threshold is even lower in the Stop Predatory Investing Act that was introduced in March, which names "disqualified single family property owners," defined as taxpayers who directly or indirectly own 50 or more single-family residential rental properties.

"There's a lot of rich families that would fall into that category inadvertently because they are real estate developers and made their money in real estate," said Odette, a partner at Haynes Boone who advises family offices, funds and institutional investors.

Family offices generally prefer multifamily housing and commercial developments, she said. However, there are some family offices, especially in the South, that have meaningful portfolios of single-family homes in suburban or rural areas, she said.