BEIJING -- The China Investment Corporation, the nation's sovereign wealth fund, announced Thursday that the annualized yield of its overseas investment stood at 3.9 percent since it was founded five years ago.

The company said the result showed that the corporation has maintained and increased the value of the nation's foreign exchange reserves amid fluctuating global financial markets.

According to the company's 2011 business report, its overseas investment portfolio included 31 percent of long-term investments, 25 percent of diversified public equities, 21 percent of fixed-income securities, 12 percent of absolute return investments, and 11 percent of cash funds and others.

Due to the slow recovery of global economy and the European debt crisis, the return on the CIC's global investment portfolio declined 4.3 percent last year.

Headquartered in Beijing, the company was established on Sept 27, 2007 with a registered capital of $200 billion. Its total assets reached $482 billion as of the end of 2011.