The public disclosures of the five largest pension fund organisations were reviewed. All organisations reviewed manage funds backing the pension entitlements of public sector workers. The United States has a large, mature and fragmented pension market. Many states as well as some counties and municipalities have one or more plans for their public sector employees. Private sector pensions are provided by employers or employer/employee associations. On a federal level, social security provides retirement and other benefits, paid by a combination of payroll taxes and a reserve fund.  

Historically, defined benefit plans were the predominant type of retirement plan for both public and private sector workers. Since the turn of the century there has been a concerted move away from defined benefit structures to cash balance and pure defined contribution structures among private sector employers. Pension arrangements for public sector employees are still commonly defined benefit plans, although the last 10 years has seen hybrid defined benefit/defined contribution designs become more common.

Pension arrangements in the United States are highly regulated. Private sector arrangements are governed by ERISA whereas public sector pensions follow regulations determined by the respective state legislative bodies. In addition to these regulations, pension plans must also abide by tax regulations. In fact, it is sections of the US tax code that give rise to the names of many defined contribution arrangements in the US such as 401(k), 403(b), and 457 plans.