Hypothetical: SS revenues this year are larger than outlays. So Treasury
takes in the extra SS money from individuals and puts it into an account.
You might think of it as an escrow account -- only it can't be, actually,
because there is no higher bank or other place they can deposit that money
to assure it's going to stay there. So they just put it in something like a
federal banking reserve account (let's not get the Fed involved here unless
you really want to). Treasury itself is keeping the account.

What has actually happened? The account is not a demand account -- it
doesn't "belong" to any individual or institution. Any claims against it are
theoretical; they occur in the future, and ONLY if the actuarial guesswork
was right. No one can withdraw from it on demand or use it as collateral.
It's no longer part of the money supply. It's dead numbers on a page.

Ed. As a hypothetical, because it's never going to happen in our
lifetime. What would happen if that enormous sum of money were
invested by buying stocks and bonds of US companies, or all over the
world if the amount of money were too large for the US economy?

I haven't been reading on this, so there may be a downside that I
don't know about, but my intuition is that it would put the money to
useful purpose by allowing business to expand.

RWL