[freyr]

AirBNB involves a negligible fraction of the city's housing units.

A more relevant metric would be the AirBNB rentals relative to the vacant rental units. A rough estimate indicates:

- There are 300+ "Entire home" units available in SF next week on AirBNB. AirBNB says this represents 15% of the total supply. This would suggest there are 2,000+ such units in total registered on AirBNB (though I presume some of those are occupied units that are only listed when their occupants are out of town).

- The rental vacancy rate in San Francisco is 3.6% of 220,000 units, or about 8,000 vacant rental units total.

- This suggests that the percentage of unoccupied units that are serving as AirBNB units ranges from 3.6% (300/8300) to over 20% (2000/10000) Even at the overly conservative rate of 3%, this is a non-negligible fraction in a city with a rental shortage. Rents tend to jump sharply when the rental vacancy rate falls too low, and SFs vacancy rate is among the lowest in the nation.

Surely the commenter upthread was talking about the moratorium on development in the Mission.

You're likely right.

[arebop]

Suppose ABNB shuts down tomorrow and all the owners decide to put their units on the long-term rental market instead. OK, you've got your 20% bump... for one week. The open house starts, an hour later those units are all rented, and how do you suppose prices look the next month? 2000 units of rental housing is 2000 units of rental housing. The right comparison is between the number of units used for short-term vs. long-term housing, not between the number of units used for short term rental and the number of long term rentals available right now.

[freyr]

No. There is constant churn of long-term apartments being leased and vacated. If you increase the total supply of long-term apartments, this affects the rental market from that point forward.