Cathie Wood's Ark Investment Management bought over 365,000 shares of its own ARK 21Shares Bitcoin ETF worth $16 million. It did this by selling a similar amount of shares in the ProShares Bitcoin Strategy ETF from its ARK Next Generation Internet ETF fund. This early support from a sister fund could help ARKB gain scale quickly against other newly launched spot Bitcoin ETFs. Demand appears strong for the ETFs overall, with an estimated $803 million net inflows in the first 3 days, led by BlackRock's $710 million. Grayscale Bitcoin Trust saw over $1.2 billion drained, corresponding to the ETF launches.