Cathie Wood's ARK Innovation ETF (ARKK) just set two records in two days, and they moved in opposite directions.
The fund pulled in $4.6 billion late last week, its biggest single-day inflow ever. The next session, it lost $6.2 billion in its biggest single-day outflow ever - and in between, SpaceX went public.
The trade has a name: IPO arbitrage. Investors dump cash into an ETF that they know is getting an IPO allocation, wait for the fund to receive its shares, then pull the money back out once the stock starts trading.
The payoff: indirect exposure to a hot listing they couldn't easily buy on their own.
ARKK picked up about 1.7 million SpaceX shares on listing day, and Bloomberg's flow data points to large institutions moving in and out through the fund's creation-and-redemption plumbing - the same internal mechanism ETFs use to issue and retire shares - rather than buying ARKK on the open market.
"Investors appear to be using ARKK as a piggyback vehicle for access to opportunities they may not be able to easily buy directly," said Bloomberg Intelligence ETF analyst Athanasios Psarofagis.
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The losers in this trade are the investors who actually wanted to own ARKK in the first place. When billions rush in right before an IPO and rush back out right after, existing holders get a smaller slice of the new stock and any first-day pop gets watered down across all that extra cash.
One fund manager pushed back. Joel Shulman of ERShares blocked new shares of his $2.4 billion XOVR ETF from being created the week before SpaceX listed, then added a 2% fee on redemptions to keep the trade out.
He says the move turned away more than $1 billion in potential inflows.
"We stopped the creations the week before the IPO, and the intent was to protect our long-term loyal shareholders from dilution," Shulman said.
This is the third time in recent months that ARKK has seen this kind of whipsaw around a new listing, with the same fingerprints showing up around the X-Energy debut in April and the Cerebras Systems debut in May.
A similar setup appeared earlier in 2025 around Bullish and Klarna, though ARKK didn't end up with Klarna shares - meaning whoever placed that bet ate the costs for nothing.
Other funds that got SpaceX allocations show the same pattern, including two other Ark products and Baron Capital's First Principles ETF.
SpaceX was the largest listing in history, and it probably won't be the last time this trade shows up.
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