"Money" is a much squishier concept. There is no "market cap" for dollars from which you can compute a fraction. In fact, the most common measures of "money s

"Money" is a much squishier concept. There is no "market cap" for dollars from which you can compute a fraction. In fact, the most common measures of "money supply" view securities as resources/property/objects and not money. In fact in fact, the purchase/sale of a debt security like a bond is the primary way that money is "created" in the economy. The closest you could come to answering this question would be to ask Fidelity, Vanguard, etc... how much of their investment account balances are held in ETFs. I have no idea what the answer is.