Baby Boomers have been retiring for quite some time already. The Baby Boom was from 1946 to 1964[1], so the oldest Boomers are now 77 (well past the usual retirement age) and the ones in the middle are around 68 (many have retired already).

[1] https://en.wikipedia.org/wiki/Baby_boomers

Sounds plausible, any idea what proportion of the large index funds they are thought to own? In the same vein, I wonder if pension funds can pose a risk or if they are self perpetuating enough to not cause any fire sales.