LONDON: Glencore International AG, the commodity trader that's considering an initial public offering, may grow to rival the world's largest mining companies, according to investor Nathaniel Rothschild.

The Baar, Switzerland-based company is at a "crossroads" in its development, said Rothschild, who bought $40 million of Glencore bonds convertible into shares upon an IPO. Glencore said last month it sold as much as $2.2 billion of the bonds.

A share offering would end more than three decades of the company operating as a closely held partnership. Glencore trades metals and oil and owns mines and smelters. It has a 34 percent stake in Swiss mining company Xstrata Plc.