Monthly since 2010 — latest point: Jun 2026 (inventory 2,603 mn bbl, Brent $85.4)
Rule of thumb: every 100 mn barrel draw in OECD commercial crude inventories ≈ +$13.8/bbl on Brent (and symmetrically, a 100 mn barrel build ≈ -$13.8/bbl).
Sanity check: inventories fell from 2,824 mn bbl (Feb 2026) to 2,603 mn bbl (Jun 2026) — a 221 mn barrel draw — which the regression would put at roughly +$31/bbl, while Brent actually moved from $71 to $85, a $15/bbl jump. The actual move ran hotter than the historical relationship alone would predict — consistent with a geopolitical risk premium layered on top of the inventory effect.