Models each discrete forward rate L_i(t) = L(t; T_i-1, T_i) as log-normal under its own forward measure mathbbQ^T_i: dL_i(t) = σ_i(t) L_i(t),dW_t^T_i, recovering Black's caplet formula by construction. Under a single terminal measure the drifts become non-zero and tenor-dependent (LMM drift cascade). Calibrated jointly to ATM cap and swaption vols; instantaneous-correlation matrix among forwards drives swaption smile. Post-LIBOR the analogue prices SOFR-based caps and term-SOFR products.