I'm sure they did. Coinbase was grossly undervalued for a while. They have the longest and best track record of any exchange, so it made sense for them to be the custodian for these ETFs. Gotta have a solid spot market to have a spot ETF. Buying Coinbase is the safe play.

Blackrock will collect a small fee on this ETF for doing literally nothing. 0.59% I think is what I saw. They'll pay a small fee to Coinbase for the cash in/out conversions. Coinbase makes a mint by charging this to all the ETFs. So might as well own the custodian too.

Blackrock bought in early as soon as they decided they were going to use Coinbase as their custodian. The more recent +150% in COIN stock was the rest of Wall Street figuring out the same play.