Bitcoin trades 24 hours a day, but its price movements are becoming increasingly concentrated around the US trading session, according to a study of activity between 2016 and 2025.
The nine hours from 13:00 to 21:59 UTC accounted for 50.6% of Bitcoin’s daily realised variance between 2022 and 2025, compared with 38.4% in 2016-2018. That period represents only 37.5% of a full day.
Researchers examined 87,672 hourly observations from Kraken’s XBT/USD market. They found that Bitcoin’s volatility peak now shifts with New York’s daylight-saving changes and weakens when the New York Stock Exchange is closed.
The development coincides with the wider institutionalisation of cryptocurrency through regulated futures, publicly traded companies and US-listed investment products. The study did not identify one definitive cause, with ETF flows, futures trading, market-maker hedging and other institutional activity all possible factors.
Bitcoin’s volatility moves with the US session
During 2022-2025, Bitcoin’s most volatile hour moved from 14:00 UTC during US daylight-saving time to 15:00 UTC during standard time. The variance-weighted centre of the US trading window also moved 0.33 hours later, a statistically significant change.
No similar response to changes in the US clocks was found in 2016-2018.
NYSE holidays provided another indication of the link. On weekday US market holidays during the later period, the proportion of Bitcoin’s variance occurring during US hours fell by 13.9 percentage points, from 55.7% to about 41.9%. That was close to the 37.5% expected if volatility were evenly distributed across the day, making the difference statistically insignificant.
Bitcoin’s variance-weighted centre shifted from 14.1 UTC in 2016-2018, near the overlap between London trading and the New York open, to 17.1 UTC in 2022-2025. The study’s concentration index rose by more than 40%.
Change began before US spot ETFs
The research found November 2021 was the main statistical break in Bitcoin’s US-hours volatility trend. It found no comparable change around the December 2017 launch of CME Bitcoin futures or the approval of US spot Bitcoin ETFs in January 2024.
Using all data before and after the ETF launch suggested a 9.6-percentage-point increase in the US-hours share of variance. But a symmetric 12-month comparison showed a rise of only 0.1 percentage point, with no statistically significant break. The equivalent CME futures comparison fell from 7.1 points to 0.3.
When researchers tested 1,000 randomly selected dates as supposed market-changing events, the broad method showed significance at the 0.1% level for every date. The symmetric method did so in only 4.7% of cases.
The shift also appears across the week. Bitcoin’s weekend-to-weekday volatility ratio fell from 0.96 in 2016 to 0.60 in 2024 and 0.64 in 2025. The volume ratio dropped from 0.78 to 0.43 in 2024, before reaching 0.46 in 2025.
Similar US-hours trends were found in six of seven other long-listed assets on Kraken, including Ethereum, XRP, Solana, Cardano, Dogecoin and Chainlink. XRP’s share rose from 37.2% to 46.2%, while Ethereum’s increased from 41.8% to 48.2%. Litecoin was the only asset without a statistically significant trend.
The study used one exchange and ended in 2025. Further multi-venue and order-book research is needed to establish how much of the change comes from ETF activity, derivatives, hedging or other institutional flows.
