Coinbase's Bitcoin premium index remained negative for 86 straight days from May 19 through Aug. 12, the longest such stretch on record, with the CoinGlass gauge at -0.1027% as of 8:30 a.m. UTC on Aug. 12. The previous record was a 40-day run from Jan. 16 to Feb. 24. A reading below zero means Bitcoin is trading cheaper on Coinbase than on other major exchanges, a pattern often associated with weaker U.S. buying pressure, softer institutional demand or relatively heavier selling by American investors. Analysts say the unusually long streak points to persistent caution in the U.S. spot market, with intermittent outflows from spot Bitcoin ETFs broadly matching the trend, although arbitrage, liquidity conditions and regulatory developments can also affect the premium.