We recently renegotiated our rent for a 2br apartment in SF about 7% down after having begun our lease in March. Used a 2 prong tactic of mentioning some frustrations that we've had thus far as well as offering to extend our lease. We didn't have much leverage, but offering something in exchange for the rent reduction was probably what convinced them.

I re-negotiated my 2B2B rent down from $4700 to $4200, and honestly could've gone lower (landlord accepted our first offer).

The most important thing for me in this process was doing the research on comparable properties in the city and spreadsheeting it out (sqft, rent, location, and amenities). I presented that spreadsheet, showing there were obviously places I could move to that were much cheaper with similar to better benefits.

Ultimately all negotiation is about showing that you're willing to walk away for a better alternative, and it's pretty clear there were good alternatives given the current SF housing market.

Trying to do this now. They aren't budging on the rent, but are pitching a reduction to removal of parking and pet fees. I don't know if this is because they fall out of rent control regulations. Was aiming for a 10% total reduction, but they've effectively hit a 4% reduction in my case.