The logo of Singapore's sovereign fund GIC.

Singapore's GIC is taking the unusual step of investing directly in unlisted firms, a move bankers say will be mimicked by other sovereign wealth funds as low yields spur fund managers to adopt a more hands-on attitude in their search for higher returns.

In the first half of this year, GIC agreed to pay up to $310 million for minority stakes in two unlisted Philippine companies: food producer Century Canning and hospital group Metro Pacific Investment.