Despite significant inflows into Bitcoin ETFs over the past 19 days, Bitcoin's spot price has remained stable. This stability is attributed to large hedge funds simultaneously buying ETFs and selling futures contracts, neutralizing the potential impact of ETF inflows on the spot price.

Crypto investment firm CMS Holdings highlighted this phenomenon, noting that hedge funds have increased their net short positions in CME standard Bitcoin futures contracts to a record 18,175 contracts, according to the Commodities Futures Trading Commission Commitments of Traders report.

This rise in short positions is likely tied to the basis trade strategy, where hedge funds buy Bitcoin through ETFs, which closely track the spot price, while selling futures contracts. This approach allows hedge funds to profit from the narrowing price gap between futures and spot prices, especially as futures contracts near expiration.

Prime brokers' acceptance of Bitcoin ETFs as collateral has potentially enabled larger scale basis trades, as mentioned by the research arm of crypto derivatives exchange BitMEX.

Overall, the selling pressure from the futures market offsets any potential upward movement from ETF purchases, as reflected by fluctuations in futures Open Interest (OI), indicating diverse trader sentiments on short-term price movements.