LONDON: Saudi state oil company Aramco has started trading a US crude oil grade that underpins the global Brent benchmark in a process run by S&P Global Commodity Insights, the publisher said on Monday, according to Reuters. Aramco, the world"s largest oil company, has been expanding its trading activity. The company could not immediately be reached for comment by Reuters on Monday after Saudi business hours. On Monday, Aramco sold a cargo of US WTI Midland crude to Total in the Platts Market on Close process, known as the Platts window, trade sources said. Aramco had last Thursday sold another cargo of the US crude. These were Aramco"s first WTI Midland trades in the MoC, Joel Hanley, S&P global director of crude and fuel oil markets, said via email. In December, Aramco bought a cargo of North Sea crude DUC, its first deal since joining the process, he said. US WTI Midland is one of six crude oil grades assessed by Platts that can set the value of dated Brent, part of the wider Brent complex used to price over three-quarters of the world"s traded oil.