While Greystar maintains it has been proactive in improving fee disclosures and promoting transparency, the company noted the lack of clear regulatory guidelines in the rental space. The potential lawsuit is part of a broader regulatory crackdown on big corporations under FTC Chair Lina Khan and President Biden's administration.

The antitrust agency recently created a rule regarding junk fees, but its application to the multifamily sector is unclear.

Greystar is set to face a federal lawsuit as soon as this week over allegations the nationwide developer and manager of apartment buildings stuck renters with millions of dollars in hidden fees, according to people familiar with the probe.

The suit accuses the company of falsely advertising rental prices by failing to inform renters of numerous mandatory fees.