Say they acquire both Grey Scales Trust of GBTC and the goverments silk road stack OTC (off market) they would easily have 2% without moving the market price.
Then say they hammer sell BTC original after the fork... think stock to flow... ~2.2 million coins currently on market, the new flow to stock is 20%
They would have to aggressively aquire their bitcoin BR, sure, but they will pull every dirty trick in the book limiting sells.
The SEC is 100% captured and on board with Blackrock