The return rate of China's Social Security Fund may decrease this year because of the downturn in the country's stock market, Dai Xianglong, chairman of the fund and a former central bank governor, said on Monday.

Dai is also a delegate to the ongoing 18th National Congress of the Communist Party of China.

The yield of the 1.037 trillion yuan ($166.5 billion) fund is expected to fall to 5 percent this year, mainly due to the lackluster situation in the domestic stock market, Dai said. However, he expects the market to regain momentum next year.

The average annual yield of the Social Security Fund was 8.4 percent at the end of 2011, with accumulated earnings on investment of 284.6 billion yuan, among which 132.6 billion yuan, or 46 percent, came from stock market investments.

China’s A-share market has decreased 5.46 percent since the beginning of the year.

The long-term return rate of the Social Security Fund is 6 percentage points higher than the inflation rate, Dai was quoted by ET Net as saying.

Dai said that he is confident that the fund will be able to maintain a balance between payments and earnings in the long term, as well as keep a positive yield.

He also said that the fund’s portfolio is not expected to change significantly next year, and that it will follow a diversified approach in its investments.

Apart from stock market and direct investments, fixed-income products account for half of the fund’s basket.