No difference

The "full moon makes markets wild" folklore

Trading folklore has long held that full and new moons mark turning points, and moon-phase chart indicators abound. Academia has tested "lunar phases and stock returns" seriously — a few papers in the 2000s reported small correlations, but later large-scale replications mostly failed to reproduce them. This page runs that question automatically, every day, for two major currency pairs (USD/JPY and EUR/USD).

How this verdict is computed

• Data: the European Central Bank's daily reference rates (since 1999) — the widely cited official fixings
• We test the size of moves, not their direction: each trading day's absolute percentage change from the previous day
• FX volatility carries strong weekday patterns (Monday gaps, jobs-report Fridays), so each day is compared with the average for the same "weekday × month" combination — the same adjustment used on the births page
• Days are classified as full moon days (±24h around the instant) or new moon days using the moon age at the ECB fixing time (early afternoon CET); each group's mean index is compared with 1.00

See the methodology for the exact criteria.

Please note

• This page presents historical statistics, not investment advice. Even if a verdict ever moves away from "No difference," that would not imply a tradable edge (after transaction costs, a few percent of volatility difference has essentially no economic value)
• We make no claims about moon-phase trading systems. The only question tested here is whether currencies visibly move more on calendar full moon days

What we can't see yet

This result doesn't mean "the moon has nothing to do with it." Here is what the current method can't see:

• Moves within the day: we use one price per day. Big swings during the day don't show in a single fixing
• Other markets: for now we look only at currencies

What we want to check next

• Test the daily high-low range
• Run the same test on stock indexes and other markets

Perhaps the long-told market lore holds something we haven't yet turned into numbers. We'd like to find it in the data one day.

Sources

• ECB Euro foreign exchange reference rates (via the Frankfurter API)
• Moon phase instants computed in-house from Jean Meeus, "Astronomical Algorithms" (UTC)