Direct Answer
Life and health insurance companies pool mortality risk (life insurance pays when policyholders die) and morbidity risk (health/disability insurance pays when policyholders become sick or disabled) across large numbers of policyholders. MetLife, Prudential Financial, Lincoln National, Principal Financial Group, and Unum Group are major US-listed life and health insurers. Unlike property-casualty insurers (which pay short-tail claims), life insurers manage long-duration liabilities (30-40 year insurance policy obligations) against long-duration investment portfolios, making interest rate sensitivity a central risk factor.
Life Insurance Products: Term, Permanent, and Annuities
Life insurance companies offer several product types with fundamentally different economic characteristics. Term life insurance pays a death benefit if the insured dies during a specified term (10, 20, or 30 years); if the insured survives, no benefit is paid and premiums are not returned. Term life is essentially a pure mortality risk transfer: the insurer bets (statistically, across millions of policyholders) that most policyholders will survive their term, and prices premiums to cover expected deaths plus expenses and profit. Term life margins are thin and commoditized -- insurers compete primarily on premium pricing driven by actuarial accuracy in mortality assumptions.
Permanent life insurance (whole life, universal life, variable universal life) combines death benefit protection with a cash value savings component that builds over time. The policyholder pays higher premiums than term insurance; the excess over mortality cost is invested by the insurer and credited to the policyholder's cash value account. The insurer earns a "spread" between what it earns on investments and what it credits to policyholders -- a spread business analogous to a bank. Permanent life creates long-duration liabilities: a 35-year-old who buys whole life creates an obligation that may last 50 years.
Annuities (fixed annuities, variable annuities, indexed annuities) are retirement income products that are economically the opposite of life insurance: life insurance pays out when you die (young death is a loss for the insurer), while annuities pay out as long as you live (long life is a loss for the insurer, which must keep paying). Annuities are essentially longevity insurance -- the individual transfers the risk of outliving their assets to the insurance company. Fixed annuities guarantee a specified payout rate; variable annuities link payouts to investment performance with optional guarantees (living benefit riders).
The Investment Portfolio: How Life Insurers Make Most of Their Money
Life insurance companies collect premiums today and pay claims in the future -- for life insurance, potentially decades in the future. The assets collected from policyholders before claims are paid constitute the investment portfolio, typically invested in high-quality bonds (investment-grade corporate bonds, mortgage-backed securities, government bonds, and commercial real estate loans). The investment portfolio of a large life insurer is enormous relative to its equity capital: Prudential Financial's general account investment portfolio exceeds $400 billion. The spread between the investment return earned on this portfolio and the obligation owed to policyholders (credited interest on annuities, reserves built up for future death benefits) is the primary driver of life insurer profitability.
This investment-spread model makes life insurers highly sensitive to interest rates. When interest rates rise, newly-purchased bonds earn higher yields, expanding the spread between earned investment returns and credited policyholder rates -- beneficial for profitability. But rising rates also reduce the mark-to-market value of existing bond portfolios (bond prices fall when rates rise), which may create accounting losses and capital constraint if bond holdings must be marked to market. Sustained low interest rates (as in 2010-2021) compress life insurer spreads as existing bonds mature and must be reinvested at lower yields, while policyholder obligations remain fixed or decline only gradually. The 2022-2023 rate rise environment was thus structurally positive for new investment income in life insurance, though it created some unrealized losses on existing portfolios.
Group Employee Benefits: The Stable Revenue Base
Group life insurance, group disability insurance (short-term and long-term), and group dental/vision insurance sold to employers for their employee benefit packages represent a significant and relatively stable portion of major US life insurer revenue. Unum Group is the largest US provider of group disability insurance; Lincoln National, MetLife, and Hartford Life are major group life providers. Employers purchase group benefits contracts annually during open enrollment periods, creating recurring, predictable revenue streams that are less sensitive to individual mortality or morbidity experience than individual life policies (the large group sizes diversify idiosyncratic risk).
Group disability insurance (LTD -- long-term disability) is economically interesting: it pays income replacement to employees who become disabled and cannot work, for periods potentially lasting years or decades. The insurer's risk is morbidity (illness and injury leading to disability) rather than mortality. LTD claims management -- rehabilitation programs, return-to-work coordination, medical case management -- is a core competency that determines profitability: getting a disabled claimant back to work one year earlier (or preventing a fraudulent/malingering claim from extending) is worth years of premium income. Unum's scale in disability insurance gives it superior claims management data and processes that are difficult for smaller competitors to replicate.
Investment Considerations: Interest Rates, Long-Duration Liabilities, and Reserve Adequacy
Life insurance is among the most interest-rate-sensitive financial services sectors. The asset-liability management challenge -- matching long-duration liabilities (30-40 year insurance obligations) with long-duration assets (long-maturity bond portfolios) -- means that large interest rate moves create both opportunity (higher new money yields) and risk (unrealized portfolio losses, potential policyholder behavior changes such as surrendering policies when rates are high to reinvest elsewhere).
Reserve adequacy is the central credit risk for life insurers: if the actuarial assumptions embedded in policyholder reserves prove wrong (mortality improves faster than expected, annuity holders live longer than expected, disability claims severity is higher than modeled), the insurer must increase reserves by taking income statement charges. The 2008-2009 financial crisis exposed life insurers with excessive exposure to mortgage-backed securities and equity-linked variable annuity guarantees; the long-duration nature of insurance liabilities means mistakes compound over decades. Evaluating life insurer book values and reserve adequacy requires understanding actuarial assumption sensitivity -- a discipline that differs significantly from typical equity analysis frameworks.
FAQ
How do life insurance companies make money?
Life insurance companies generate profit from two distinct sources. First, underwriting profit: premiums collected exceed claims paid plus expenses. For term life insurance (pure mortality risk), this means pricing premiums accurately to cover expected deaths (based on age, health, smoking status, mortality tables) and administrative costs, with the surplus being profit. For permanent life and annuities, underwriting involves more complex long-term actuarial modeling. Second, investment income spread: life insurers invest the premiums they collect (and the reserves built for future claims) in bonds and other assets, earning an investment return. On permanent life policies and annuities, they credit a portion of that return to policyholders and retain the difference as spread income. A life insurer investing policyholder assets at 5% and crediting 3.5% earns a 1.5% spread on its general account portfolio. For large insurers with hundreds of billions in invested assets, even modest spreads generate significant dollar income. The investment income component typically dominates life insurer earnings -- underwriting profit alone is often modest; the investment portfolio returns are the primary profit driver, making life insurers essentially leveraged investment companies with insurance obligations as their liability.
Why are life insurers so sensitive to interest rates?
Life insurance companies borrow money in a sense -- they collect premiums today and promise to pay claims in the future, sometimes 30-40 years from now. The "interest rate" they must earn on their assets to meet those future obligations is embedded in the pricing and reserving of their policies. When interest rates fall (as happened from 2010-2021), life insurers face a mismatch: their fixed obligations to policyholders (minimum credited rates on permanent life, guaranteed annuity payout rates) don't fall proportionally, but their investment income declines as bonds mature and must be reinvested at lower yields. This margin compression reduces profitability and, in severe cases, can threaten solvency if earned returns fall below the rate guaranteed to policyholders. When interest rates rise (as in 2022-2023), life insurers benefit: new investment income rises as portfolios are reinvested at higher yields, expanding the spread between earned returns and policyholder obligations. However, rising rates reduce the mark-to-market value of existing bond portfolios (bonds lose value when rates rise), creating unrealized losses that reduce reported book value and may constrain capital ratios under accounting standards that require marking assets to market. The duration mismatch -- how long liabilities last versus how long assets last -- determines the sensitivity magnitude. A life insurer with 15-year average liability duration and 10-year average asset duration is exposed to rising rates widening that gap; one with perfectly matched durations is largely rate-neutral.
What is long-term disability insurance and how is it different from life insurance?
Long-term disability (LTD) insurance replaces a portion of an employee's income (typically 60-70%) if they become unable to work due to illness or injury, for periods that can extend until retirement age (age 65 or 67) in severe cases. It is fundamentally different from life insurance in the risk being insured: life insurance pays upon death (mortality risk); disability insurance pays when the insured is alive but unable to work (morbidity risk). LTD is also different in claim duration and management intensity: life insurance pays a lump sum at death (relatively simple claim); LTD involves ongoing monthly benefit payments that continue as long as the claimant remains disabled, which requires ongoing medical evaluation and claim management to verify continued disability. The insurer's economics are therefore heavily influenced by how well it manages claims -- identifying when conditions improve, facilitating rehabilitation programs, coordinating return-to-work plans, and detecting fraudulent or malingering claims. Companies like Unum Group (the US LTD market leader) have built proprietary claims management systems and databases over decades that allow them to price disability risk more accurately and manage claims more efficiently than smaller competitors, creating genuine competitive advantage in what would otherwise be a commoditized benefit.
How does a life insurer's book value differ from other financial companies?
Life insurer book value is more complex than a bank's or property-casualty insurer's because it reflects decades of long-duration policy obligations and the assets matched against them. Three specific complexities matter for investors. First, accumulated other comprehensive income (AOCI): life insurers hold massive bond portfolios that are marked to market on the balance sheet, with unrealized gains/losses flowing through AOCI (a component of equity). When rates rise (as in 2022), bond values fall, AOCI turns sharply negative, and reported book value per share declines significantly -- even though the company's underlying business hasn't changed (those bonds will mature at par value if held to maturity). Analysts typically look at "book value excluding AOCI" for a more stable business view. Second, actuarial reserves: the liability for future policy benefits is estimated using actuarial models with assumptions about mortality, morbidity, interest rates, and policyholder behavior. Changes in these assumptions (or required updates under accounting rules like LDTI -- Long Duration Targeted Improvements, adopted in 2023) create large book value movements that don't reflect cash flows. Third, intangibles: deferred acquisition costs (DAC, representing the capitalized cost of selling policies) and value of business acquired (VOBA, for acquired policies) are significant intangibles that reduce book value when written down. These complexities explain why life insurance stocks often trade at 50-80% of book value -- investors apply a discount reflecting uncertainty about reserve adequacy and actuarial assumptions.