China's National Council for Social Security Fund (NCSSF), said Thursday that its assets under management reached 868.9 billion yuan (137.14 billion U.S. dollars) as of the end of 2011.

Of the total assets, direct investment assets totaled 504.2 billion yuan, or 58.03 percent, while entrusted investment assets stood at 364.7 billion yuan, or 41.97 percent, Dai Xianglong, chairman of the NCSSF, said during a board meeting.

In a breakdown by investment sector, the proportion of assets with fixed income was 50.66 percent, while that of stock assets was 32.39 percent.

Industrial investment accounted for 16.31 percent of the total, with the remaining 0.64 percent in cash and cash equivalents.

The central government has allocated a total of 492 billion yuan to the NCSSF as of the end of 2011, with 189.8 billion yuan from the central budget, 90.3 billion yuan from lottery sales and 16.1 billion yuan from state-owned shares, Dai said.

Dai said the fund's average annual earning rate over the past 11 years stands at 8.41 percent, 6 percentage points higher than the average inflation.

In 2011, the fund's investment income stood at 43.1 billion yuan, with a yield rate of 5.58 percent.

Dai said the fund started investing in the stock market in 2003 and has earned 132.6 billion yuan from the market, or 46 percent of its total income, marking an annualized return rate of 18.61 percent.

Founded in 2000, the social security fund managed by the NCSSF is designed to serve as a solution to the country's aging problem and a strategic reserve to support future social security expenditures.