Lol, I wonder how these 'paper Bitcoin' fanatics in the comment section here imagine how these ETFs eventually cash out their selling clients. If I was an ETF operator I'd be really stupid not to buy the real Bitcoin. What else was I gonna do with my clients money? You're gonna go bankrupt pretty quickly if you didn't own the underlying. And the higher Bitcoin went, the quicker you get liquidated. If Bitcoin went 10x, only 10% needed to be sold for bankruptcy.

I conclude the ETFs fully own the underlying.