Per the next 3 charts: Comparing September 2018 with September 2017, the number of new listings in Marin was up 6%, price reductions on active listings were up 21%, and the number of active listings on the market on a given day within the month was up 44%.
Other Bay Area counties generally saw more dramatic changes in inventory than Marin did, which is illustrated in the table following the charts. Not too much should be made of any one month's data until substantiated over the longer term, but it may be that after a torrid, low-inventory market, autumn 2017 through spring 2018, the dynamics are starting to shift. We will know more in 4 to 6 weeks.