From Bloomberg Law:
You can read the filing here, and it includes gems like the following:
“…beginning in approximately 2016, and potentially earlier, Lessors replaced their independent pricing and supply decisions with collusion. Lessors agreed to use a common third party that collected real-time pricing and supply levels, and then used that data to make unit-specific pricing and supply recommendations. Lessors also agreed to follow these recommendations, on the expectation that competing Lessors would do the same.”
…
“As of December 31, 2019, RealPage had over 29,800 clients, including each of the ten largest multifamily property management companies in the U.S.”
There's also additional reading on the matter: