Paris-listed buyout group Wendel has increased its stake in French glassmaker Saint-Gobain for the second time since its initial investment, despite analysts' criticisms that its move away from traditional private equity investing would increase risk.

Wendel said this morning it had increased its stake in the company to 15.5% of Saint-Gobain's capital and 14.8% of the voting rights. The increase means Wendel now owns 58.1 million shares worth about €4.3bn ($6.3bn), it said.