The head of Glencore's huge coal-trading operation is leaving in the biggest shake-up of the company’s trading unit in years.

The news comes after Glencore, an historic name in commodity trading that traces its history back to the industry’s godfather Marc Rich, disappointed investors with weak results for the first half of the year and is facing internal and external pressure to revive its moribund share price.

Ruan van Schalkwyk, a longstanding executive who runs coal trading for Glencore, is retiring, according to a memo from CEO Gary Nagle, that was seen by Bloomberg News. Glencore is the world’s largest shipper of coal.

At the same time, Jyothish George, currently head of copper and cobalt trading, will take on a wider role as head of metals, iron ore and coal trading, according to the memo. Several trading executives who currently report to Nagle will now report to him, including Peter Hill, the head of iron ore, and Robin Scheiner, head of alumina and aluminum.

Alex Sanna, who runs oil, gas and power trading, will continue to report to Nagle.

Under George, trading responsibilities are being reassigned. David Thomas, currently head of ferroalloys trading, will take over thermal coal. Paymahn Seyed-Safi will have responsibility for chrome as well as nickel; and Hill will take over responsibility for vanadium and manganese as well as iron ore.

The changes come after Glencore’s trading teams reported starkly different results for the first half of the year. The company’s metals traders notched up their best half-yearly performance on record, while their energy and coal-trading peers struggled to even turn a profit.

Glencore has recently significantly expanded its presence in the metallurgical coal market with its acquisition of Teck Resources Ltd.’s coal business. Nagle said in the memo that the reorganization would help align trading teams with the customers for different sets of commodities.

“We now feel the time is right to merge our steelmaking coal marketing activities with our iron ore business due to their overlapping customer bases,” he said.