What's interesting and something I've witnessed first hand in NYC, that the tenants of rent controlled apartments will setup a black market for their rent controlled apartment in collusion with their landlord. So if they do move they will attempt to sell for the privilege of renting the unit, at the time this could range as high as $50k, the landlord and previous tenant would split this 'fee'. What's incredible is that for the right apartment in the right part of NYC amortized over a few years, this was a great deal for the new tenant.