When Wall Street goes to sleep, bitcoin is usually just getting going. It often parties all night long, and in the process, notches more robust gains than while U.S. markets are open.

A hypothetical strategy that buys the coin at the equity-market close — at 4 p.m. in New York — and sells it at the next day’s open — at 9:30 a.m. — yields gains of roughly 260% going back to the start of 2020, according to Bespoke Investment Group. Conversely, buying it at the U.S. market open and selling it at the close spits out an advance of 3.6%. The coin even tends to trend higher during weekends, the firm found, when stock investors are resting or barbecuing or doing whatever weekend activities they’re fond of.

Yet no one seems to be able to agree on why this might be happening.