They're not ETFs, but SSFs (Single Stock Futures). In Europe they were called USFs (Universal Stock Futures).

There were 2 US exchanges in the past: NQLX and OneChicago, both closed now.

pros:

- short selling restrictions don't apply

- no need to locate shorts, no need to pay short interest (but of-course it's expressed in future contract's price)

- lower overnight margin requirements - only 20% vs 50% for stocks

cons:

- lower liquidity

- only round lots

- no dividends

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https://en.wikipedia.org/wiki/Single-stock_futures

https://en.wikipedia.org/wiki/OneChicago

mmmm leveraged short etfs. Total toxic waste even when you're directionally right about the underlying asset. Constantly rebalancing buying the highs and selling the lows. Only the issuer makes money on this crap.

I believe I read somewhere (wish I remembered the source) that one sign of a bubble is the concoction of ever more ways to leverage a portfolio, usually via Derivatives. Usually they do not provide something unique, and instead are created to circumvent existing legislation on securities and taxes.