The Social Security Office (SSO) was established in 1990 as a government office responsible for managing the Social Security Fund and the Workmen’s Compensation Fund. As of 31 Dec 2010, the Social Security Fund, which provides coverage to over 9.4 million private employees, has total assets of 789,181 million Baht (approx. US$25 billion). As much as 80% of the portfolio is now invested in highly secured assets including government bonds, state-enterprise bonds guaranteed by the Ministry of Finance, bank deposits, and investment-grade corporate bonds. The remaining 20% of the portfolio is invested in risky assets including other debt instruments, unit trusts (property funds and foreign investment funds), and equities. For the year ending 31 December 2010, the Social Security Fund has generated a total investment income of 33,750 million Baht (approx. US$1.1 billion). The annual investment return for the year was 8.30%. Since inception, the fund has earned an average investment return of 7.55% per year.