Dichev / Janes
Lunar Cycle Effects in Stock Returns reports a new-moon versus full-moon return gap across major U.S. indexes and international markets.
New moon market anomaly check
New moon stock-market chart going viral? Check the source trail before you post it.
TinyOps checks lunar-cycle market claims against the cited papers, sample windows, ticker/index choices, return definitions, replication gaps, and publish-safe caveats. The output is a research-verification packet, not a trading signal.
Citation trail
The broad claim has academic citations. The viral chart still needs checking.
Several papers report higher average returns around new moons than full moons in historical samples. That is not the same thing as proving a current chart, a current ticker, or a live trade setup.
Yuan / Zheng / Zhu
Are investors moonstruck? reports lower returns around full moons than new moons, with the article published in the Journal of Empirical Finance.
Floros / Tan
Moon Phases, Mood and Stock Market Returns finds market-specific full and new moon effects rather than one universal result.
Fresh replication snapshot
The current ETF check is interesting, but not a trade signal.
A TinyOps replication run on 2026-05-28 checked SPY, QQQ, DIA, and IWM adjusted closes through 2026-05-28 against simple new-moon and full-moon windows. The broad SPY half-cycle split showed a higher new-moon annualized mean, but the 2015-forward split flipped negative and the displayed tests did not survive Bonferroni adjustment.
| Result | What it says | How to use it |
|---|---|---|
| SPY half-cycle | 15.16% new-moon half versus 8.94% full-moon half, 1993-2026 adjusted closes. | A lead worth checking, not a trade rule. |
| 2015-forward SPY split | New-minus-full flipped to -4.33% annualized in the later sample. | Ask whether the chart is stable out of sample. |
| Multiple testing | Smallest displayed unadjusted p-value was 0.151; Bonferroni-adjusted minimum was 1.000. | Avoid performance claims without stricter controls. |
Method check
A publishable answer depends on the exact backtest, not the headline.
The $49 check looks for the parts that often disappear when a chart becomes social copy.
| Check | Why it matters | Output |
|---|---|---|
| Moon window | The result can change between exact phase day, +/- 3 days, 7-day windows, and 15-day half-cycles. | Window definition and caveat. |
| Return definition | Price returns, total returns, cash days, dividends, and close-to-close timing can move the result. | Return formula summary. |
| Sample and benchmark | S&P 500, ETFs, country indexes, futures, and individual stocks are not interchangeable. | Source data and scope notes. |
| Statistical strength | A pretty cumulative chart can hide weak tests, multiple-comparison risk, and unstable windows. | Plain-language evidence rating. |
Boundary
Research verification only. No investment advice.
This page exists because the claim is interesting and commercially useful to check. It does not tell anyone what to buy, sell, hold, short, copy, or trade.
- No trade alerts or strategy recommendations
- No guaranteed-return or outperformance claim
- No nonpublic information
- No portfolio routing, broker activity, or account setup
- No customer trade execution, account setup, or portfolio routing
Related source checks
Use the right source trail for the claim.
Moon-phase charts are one anomaly lane. Politician-trade claims need official disclosure filings; broad market anomaly claims need the original paper and a replication plan.
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