BTC > $78,213

Cash-or-nothing binary call: P(YES) = N(d₂), with d₂ = (ln(S/K) + (μ − σ²/2)τ) / (σ√τ). Realized vol σ_r is the annualized stdev of the past 6h of 1m log returns. Implied vol σ_iv inverts the formula assuming μ=0 (root-found by bisection). When the market price falls outside what pure diffusion can produce — typically when spot is near the strike but the market is meaningfully one-sided — we instead solve for the drift μ that matches market price at realized vol. Both views are useful; IV is the clean abstraction when feasible, drift makes the bet's directional component explicit.