First Reserve chairman and chief executive William Macaulay has bought more than £1.5m-worth of Glencore shares.
Macaulay, who has been an independent non-executive director at the troubled miner and trader since 2011, has picked up 1.7m shares, at a price of 90.9p.
It comes just two days after Glencore's chairman Tony Hayward bought 100,000 shares in the company, amid huge share price volatility, adding weight to the possibility that the firm could be leaning towards a management buy-out.
Glencore has been under pressure in recent weeks, as investors and analysts fear its ability to pay back its debt pile against the backdrop of China's economic slowdown.
The company revealed a major debt reduction plan, which includes a $2.5bn rights issue, in early September. It hopes to cut net debt to “the low $20bn by the end of 2016”.
However, analysts at both Investec and Credit Suisse have issued notes warning about the Anglo-Swiss giant's financial stability, pushing its share price down to the lowest levels since it went public in 2011.
Glencore's share price opened up, but has since dropped back down again to register a decline of 0.7 per cent at pixel time.