Understanding Pension Funds: Function, Regulation, and Investment Strategies

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A pension fund is a pool of money that an employer, a union or a government sets aside and invests to pay retirement benefits that have been promised in advance. In a traditional defined-benefit pension, the employee does not manage an account. The employer commits to a formula, usually based on years of service and salary, and the fund must hold enough assets to pay that benefit for the rest of each retiree’s life. In the United States, private pension funds are regulated under the Employee Retirement Income Security Act (ERISA) and insured by the Pension Benefit Guaranty Corporation (PBGC). Public pension funds follow state law and have no federal insurance.

How a Pension Fund Works

A pension fund has four moving parts: contributions, investments, liabilities and payouts.

Contributions. The employer pays into the fund, and in many public plans employees contribute a share of each paycheck as well. The money goes into a trust that is legally separate from the employer’s own finances.

Investments. The trust invests the contributions so that returns cover much of the future cost. Over decades, growth through compound interest often does more work than the contributions themselves.

Liabilities. Actuaries estimate what the fund will owe: how many workers will retire, at what salaries, and how long they will live. They then discount those future payments to a present value using an assumed rate of return. That present value is the fund’s liability, and the gap between it and the assets determines how much the sponsor must contribute.

Payouts. Once a worker retires, the fund pays a monthly benefit, usually for life. Under ERISA, a married participant’s default form of payment is a joint-and-survivor annuity, which continues a reduced payment to the surviving spouse unless the spouse consents in writing to a different option. Some plans also offer a lump sum in place of monthly payments.

Two rules separate pensions from personal savings accounts. First, you generally cannot take early withdrawals or loans from a pension. Second, you must be vested to keep the employer-funded benefit if you leave. ERISA sets maximum vesting schedules for private plans; for defined-benefit plans that means full vesting after five years (cliff vesting) or gradual vesting from year three to year seven.

The Benefit Formula

Most defined-benefit plans calculate the annual pension like this:

Annual pension = benefit multiplier × years of service × final average salary

Many plans use a 1% multiplier. The largest public plan in the country, the California Public Employees’ Retirement System (CalPERS), uses 2% in many cases.

Hypothetical example: an employee with 35 years of service whose five highest-earning years averaged $50,000.

• At 2%: 0.02 × 35 × $50,000 = $35,000 a year (about $2,916.67 a month)
• At 1%: 0.01 × 35 × $50,000 = $17,500 a year (about $1,458.33 a month)

The multiplier alone doubles the benefit, so the formula matters more than almost any other term when you compare two jobs that offer a pension.

Defined Benefit vs. Defined Contribution

In the corporate world, 401(k)s have largely replaced pensions, shifting responsibility for saving and investing to employees through workplace accounts and IRAs. Pensions remain common in government and some union jobs.

Public vs. Private Pension Funds

Private pension funds are sponsored by companies or groups of employers. They come in two forms:

• Single-employer plans, run by one company for its workforce.
• Multi-employer plans, which typically cover unionized workers who may move among several employers in the same industry.

Private plans seldom include a cost-of-living adjustment (COLA), so a fixed benefit loses purchasing power each year. Hypothetical example: at an assumed 3% annual inflation, a $35,000 benefit with no COLA buys roughly what $19,400 buys today after 20 years ($35,000 ÷ 1.03²⁰).

Public pension funds cover state and local employees such as teachers, police and administrative staff, and they are the largest group of active and growing pension plans. They tend to be more generous than private plans, often use higher multipliers, and usually include a COLA. The federal government runs its own pension systems for federal employees, under separate federal rules.

Regulation: ERISA and Fiduciary Duty

ERISA, passed in 1974, applies to both single-employer and multi-employer private plans. It sets minimum standards for participation, vesting, funding and disclosure, and it created the PBGC.

ERISA does not tell a plan what to buy. It requires the people who manage the plan to act as fiduciaries, putting participants’ interests ahead of their own and the sponsoring company’s, and to invest prudently and with diversification to minimize the risk of large losses. A pension fund is therefore not run for profit: the assets belong to the trust and exist to pay participants, even when the sponsor is a for-profit company.

ERISA does not cover public pension funds. Those plans follow rules set by state legislatures and, in some states, state constitutions, which may protect promised benefits from being cut.

How Pension Funds Relate to Insurance

Insurance connects to pensions in two separate ways.

The PBGC: Insurance for Private Plans

The PBGC works as a federal insurance program for private defined-benefit pensions. Employers pay it an annual premium for each plan participant. If a covered plan fails and cannot pay what it owes, the PBGC steps in and pays benefits.

The guarantee has limits. The PBGC pays up to statutory maximums that can change from year to year, so retirees with large pensions may receive less than their plan promised. It does not insure public plans; in most states, taxpayers ultimately cover a shortfall in a public employee plan.

The American Rescue Plan Act of 2021 added a program for financially troubled multi-employer plans. Eligible plans can apply for special financial assistance: a single lump-sum payment calculated to cover the plan’s obligations through 2051. The money comes from U.S. Treasury general tax revenues, not from PBGC premiums.

Insurance Companies as Pension Payers

Separately, a company can transfer pension obligations to an insurer by buying a group annuity contract. The insurer then pays the retirees’ benefits, and the obligation leaves the employer’s plan. Those retirees rely on the insurer and state insurance protections rather than the PBGC.

Investment Strategies of Pension Funds

The traditional pension portfolio splits assets among three classes:

• Bonds, which provide steady income and can be matched to expected benefit payments.
• Stocks, which offer higher long-term growth to keep pace with rising liabilities.
• Real estate, which adds rental income and diversification.

An emerging trend is to add alternative investments in search of higher returns and wider diversification, including private equity, hedge funds, commodities, derivatives and high-yield bonds. These can raise expected returns, but they also add fees, valuation uncertainty and lower liquidity.

The assumed rate of return shapes the whole strategy. A fund that assumes higher returns reports a smaller liability today, which lowers required contributions but raises the risk that actual results fall short. A fund that assumes lower returns needs more money up front. A plan with many retirees drawing income generally needs more predictable assets than a plan made up mostly of young workers.

Current Status and How to Check Your Plan’s Health

Funding health varies widely. For private plans, strain shows up in the obligations the PBGC takes on. Among state and local plans, a handful have 100% of the funding they need for estimated future benefits, while most have considerably less.

The standard health measure is the funded ratio:

Funded ratio = plan assets ÷ present value of promised benefits

Hypothetical example: a plan with $8 billion in assets and $10 billion in liabilities is 80% funded. That does not mean it will pay only 80% of benefits; it means future contributions and returns must close a 20% gap. The ratio also depends on the discount rate the plan uses, so two plans with the same ratio may not be equally healthy if their assumptions differ.

To check your own plan:

1. Read your benefit statement for your accrued benefit, vesting status and projected payment.
2. Review the annual funding notice, which ERISA requires defined-benefit plans to send participants each year with the plan’s funding percentage.
3. Look up Form 5500, the publicly available annual report private plans file with the Department of Labor.
4. For public plans, read the retirement system’s annual financial report for assets, liabilities, the funded ratio and the assumed rate of return.
5. Check the Summary Plan Description for the benefit formula, COLA terms, payout options and what happens if you leave early.

FAQs

The Bottom Line

Workers weighing a job with a pension, and retirees counting on one, should read the plan's formula, vesting rules and COLA terms, since the multiplier alone can double a benefit. Private plan members get ERISA protections and PBGC insurance up to limits, while public plan members rely on state law. Checking the funded ratio, annual funding notice and plan reports shows how well a plan can keep its promises.