ETF does not usually hold "money", so it does not make sense to ask about "percentage". ETF does however hold stocks and the like. According to BlackRock, "ETFs represent 12.7% of equity assets in the U.S., 8.5% in Europe, and 4.4% in Asia-Pacific." [1] But I think the closest should be comparing to Gold ETF since Bitcoin now is more considered to be a commodity, or event "digital gold". It would be around 2% according to Wikipedia. [2]

[1]: https://www.ishares.com/us/insights/global-etf-facts#:~:text....

[2]: https://en.wikipedia.org/wiki/Gold_holdings

"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.

$9tn - around 2.1% of global wealth. Equivalent to 4x more than the physical USD$ currency in circulation, and equivalent to around 2x the value held in deposits at commercial US banks.

Money is used to transact, it doesn't "sit" in ETFs. e.g. if I buy a share from you that money goes from person A (the buyer) to person B (the seller), it doesn't "sit" in the stock.

Now ETFs can hold some cash, but in general they're invested almost wholly in their target asset, so they hold the assets instead of cash.

You seem to be mistaking market value for money

Are you asking, of the global monetary supply of USD, how much is parked in financial vehicles that people then trade shares on to speculate its change in value rather than interest yield or dividends? Does that even exist for an inflationary currency?

Probably rather little, if money here is in general any world currency. As other instruments like debt do much better job...