@SordidAmok good question. I’d imagine the most direct way would be the find the subsidiaries owned by Blackrock and then search property records at places like the county recorder of deeds (might be online for a lot of counties).
Edit: I found more details: https://mastodon.online/@davidaugust/113529135177879898
@[email protected] “BREIT lists 267,891 units in its portfolio as of 9/30/23. https://www.breit.com/property-type/rental-housing/ This does not include Blackstone’s ownership of StuyTown (11,200 units), its purchase of the Conrad Prebys Apartments (5,800 units), and its 2024 acquisitions of Tricon Residential (37,183 units) and AIR Communities (27,010 units).” From: https://pestakeholder.org/reports/helter-shelter-how-blackstone-contributes-to-and-profits-from-californias-broken-housing-system/