I think this is a unique circumstance. Market at 15th is not really a good area IMO - while it is close to Duboce Triangle (which is very nice), the road noise from Market combined with proximity to the sketch part of SOMA[1] make it fairly undesirable. But in 2014 when the building was brand new, there were many new developments going up in that area (Whole Foods opened around that time), so my guess is buyers were betting that the area would improve rapidly, and that was priced in. 10 years later, it seems pretty clear that that optimism was misplaced, so that premium evaporated.

[1] For example, that Safeway a block away is quite rough: https://www.sfgate.com/bayarea/article/safeway-2020-market-s...

> $759/mo HOA.

That's why.