measures implied volatility, which is not directly observed but computed from an option's price using an assumed clock; this analysis counts calendar days while the market trades on business days (dte=7 is 4.76 trading sessions, dte=3 is 2.88); a zero-structure simulation containing no market behaviour at all -- constant true volatility, exact Black-76 prices on a random walk, no weekday or dte effect planted -- reproduces this pattern's published effect almost exactly (simulated +14.16% vs published +14.14%) using only that calendar-day clock; and the effect weakens to insignificance (+14.14% to +0.23%, p 0.0001 to 0.58) and reverses sign under a trading-day clock, on the real data. Not tested -- not rejected on evidence.