LONDON – Glencore reduced the role of its billionaire head of copper, Aristotelis Mistakidis, shaking up the business after a review in the Democratic Republic of Congo raised questions about accounting and management.

Mistakidis, one of Glencore’s largest shareholders and a key lieutenant of CEO Ivan Glasenberg for more than a decade, will lose control of industrial copper operations including mines and focus on the trading side of the business, according to people familiar with the plans.

Responsibility for Glencore’s copper assets will move to Mike Ciricillo, who now oversees copper smelting and refining, the people said, declining to be identified as the appointment isn’t yet public.

The shake-up reduces Mistakidis’s responsibilities after he and two other executives resigned from the board of Glencore’s Katanga Mining in Congo in November. A review by Katanga led to a restatement of its financial reporting, and a commitment from Glencore to restructure the management of its own copper business.

CLOSE RELATIONSHIP
Mistakidis, whose holding in the company is valued at about $2.5-billion, is a key part of Glencore. He’s the third-biggest shareholder among management and helped lead the company’s ascent from a scrappy trader to a diversified commodities giant and the world’s third-biggest copper miner.

For years Mistakidis, better known as “Telis,” had run both the marketing and producing sides of the copper business, a testament to his record as a trader and close relationship with Glasenberg.

Ciricillo, who ran Freeport-McMoRan Inc.’s copper operations in Congo prior to joining Glencore in 2014, takes on the new role at a critical time for the Swiss commodity giant. Glencore plans to grow global copper production by about 25% to 1.64-million metric tons by 2020, largely through the resumption of operations at Katanga.

Ciricillo will also have overall responsibility for Glencore’s lucrative cobalt output. Prices for cobalt have tripled in the last two years and Glencore, already the world’s biggest producer, wants to double production by 2019.

The shift in management structure brings the copper operations into line with Glencore’s other commodity businesses -- including zinc, nickel, coal and ferralloys -- that have separate heads of marketing and industry.

Peter Grauer, the chairman of Bloomberg LP, the parent of Bloomberg News, is a senior independent non-executive director of Glencore.