Not answerable for stocks. Real, and in the wrong asset, for metals.
The Almanac window is the last 5 trading days of December plus the first 2 of January. Tested on exactly that window, the Dow has just 9 observations and a 95% confidence interval running from 45% to 94% — it contains the claimed 80% and it contains a coin flip. What does show up is gold: up in 20 of 23 years over the same window, averaging +1.94% against a +0.33% baseline for any seven sessions. December also splits in two — gold runs −0.50% through the 15th and +1.49% after it, which is why testing December as one month finds nothing.
| Market | In the window | Rest | z | Movement | Samples |
|---|---|---|---|---|---|
| EUR/USD | 51.7% | 49.8% | 4.0 | 113% of normal | 11,869 |
| USD/JPY | 48.6% | 50.6% | -3.1 | 119% of normal | 6,700 |
| USD/CHF | 47.8% | 49.7% | -2.7 | 94% of normal | 5,592 |
| GBP/JPY | 52.0% | 50.8% | 2.0 | 113% of normal | 7,234 |
| SPX500 | 50.5% | 52.4% | -1.9 | 73% of normal | 2,907 |
| GER40 (DAX) | 50.2% | 51.5% | -1.8 | 71% of normal | 4,914 |
Stock Trader's Almanac definition · Fisher Investments (against)
Every claim here reduces to a window on the clock or the calendar, so it can simply be checked. We compare the claimed window against the rest of the week on 23 years of hourly data across 19 markets, measuring two separate things the folklore tends to conflate: direction (does the window close higher more often?) via a two-proportion z-test, and movement (is the average move bigger or smaller?). A window can be perfectly ordinary in direction and genuinely quieter in movement — saying which is the entire point.
The bar here is |z| ≥ 2, deliberately more lenient than the |z| ≥ 3 this site applies to its own numbers: when testing someone else's claim, failing to reject it even at a lenient bar is the stronger statement.