False — and it is the rare claim stated with a number.
The claim is unusually specific: "Market volatility on Tuesdays could reach 120%-130% of Monday's volatility." The page cites no source, date range or sample size. Measured across 19 markets and 23 years, the median Tuesday-to-Monday movement ratio is 0.99. Only 2 of 19 markets reach even the bottom of the claimed band. Tuesday is Monday.
| Market | In the window | Rest | z | Movement | Samples |
|---|---|---|---|---|---|
| SPX500 | 50.7% | 54.1% | -4.3 | 96% of normal | 7,884 |
| NAS100 | 51.8% | 53.9% | -2.7 | 91% of normal | 7,857 |
| ETH/USD | 49.1% | 49.9% | -1.1 | 88% of normal | 9,876 |
| US30 (Dow) | 50.9% | 51.5% | -1.0 | 101% of normal | 12,182 |
| UK100 (FTSE) | 50.2% | 51.3% | -1.0 | 96% of normal | 4,182 |
| GER40 (DAX) | 51.1% | 51.7% | -0.9 | 91% of normal | 11,398 |
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.