I'm not a specialist by any means but isn't most of the boomers' money held by pension funds and the like? Which pension funds and the like mostly use passive-investing nowadays (or techniques used by the passive-investing types, like index-tracking), which actually means buying stocks and being present on the equity markets.
What I mean is that it's not the boomers' decision to make in regards to where their money is actually invested.
Treasury bills. Very short-term government bonds that don't pay a coupon, just typically sell at a tiny discount to face value. Little risk of any kind (default, interest rate), pretty much the most secure security there is.
What I mean is that it's not the boomers' decision to make in regards to where their money is actually invested.