Mercuria trader who built huge LME aluminum bets has left

Sonny McNess, the veteran trader who helped build such massive aluminum positions at Mercuria Energy Group that the London Metal Exchange was forced to adjust its rules, has left the trading house.

Until recently a relatively minor player in metals, Mercuria’s aggressive trading over the past year has rocked the market, with the company’s aluminum position on the LME at times exceeding the total inventories in the exchange’s warehouse network.

McNess, who joined Mercuria in 2025, was already well known in metals circles for his time trading aluminum at JPMorgan Chase & Co. in the 2010s, when the bank drew attention for making big, sometimes controversial plays.

He left Mercuria in the past few weeks, according to people familiar with the matter, who asked not to be identified discussing private information. Mercuria declined to comment, while McNess didn’t immediately respond to a request for comment.

Mercuria is one of a handful of energy traders that expanded into metals in recent years to challenge incumbents Trafigura Group and Glencore Plc, making a series of high-profile hires. Last year, the company was also one of the biggest players in the tariff arbitrage trade that roiled the global copper market.

In aluminum, Mercuria built up a huge position on the LME during the first half of last year in a bet that any easing of sanctions against Russia would tighten the market. The position drew scrutiny from the LME, which imposed a new rule forcing traders to reduce large positions.

McNess’s departure comes at a time when the aluminum market is facing the prospect of a supply squeeze triggered by the conflict in the Middle East, which accounts for about 9% of global production. Two large facilities were damaged in strikes last month, while the closure of the Strait of Hormuz has restricted access to feedstock for the region’s plants.

(By Archie Hunter, Jack Farchy and Alfred Cang)