Big energy merchants trading oil cargoes that form the basis of the Brent benchmark have used an obscure clause to reroute U.S. shipments from Europe, in a practice that raises doubts over whether reforms to the crude price marker have succeeded. Brent, the most significant benchmark across commodity markets, is used to price more than 60% of globally traded crude and underpins oil futures. Platts, a unit of S&P Global Commodity Insights, last year allowed U.S. WTI Midland crude delivered to Europe to be included in its Brent price assessment, called dated Brent.