What Does a Fixed Index Annuity Actually Deliver When the Market Moves?

A fixed index annuity credits interest based on an index such as the S&P 500, but it does not give you the index return. In a down year the credit is usually zero. In an up year the credit is cut by a cap, a participation rate, or a spread that the insurer sets and can change on later anniversaries.

You pay a premium. The contract tracks the index over a term, most often one year, point to point. At the anniversary the insurer measures the index change, applies the contract limits, and adds the resulting interest to the account value. The account does not fall with the market in that period. It also does not capture the full rally. Competitive no-fee S&P 500 one-year point-to-point caps in mid-September 2026 often sit in a mid-single-digit to low-double-digit range depending on carrier, term, and whether a strategy fee is attached. Higher advertised caps frequently come with an annual fee of about 1%. The floor on most accumulation contracts is 0%.

Fees are easy to miss. Some contracts look cheap until an income rider at 1% a year starts compounding against the account. The larger cost is the cap. If the index is up 15% and the cap is 6.5%, you keep 6.5%. If the index is up 4%, you keep 4%. The insurer uses the difference to fund the floor and its own margin.

The couple in this example is unnamed on purpose. Husband 49, wife 47, two kids ages 16 and 11, Texas residents, combined W-2 income about $385,000. Home equity near $420,000 against an $180,000 mortgage. Retirement accounts about $1.1 million. Taxable brokerage about $310,000. Cash and short Treasuries about $90,000. Term life already covers the mortgage and a stretch of income. They fund 529s each year. They are weighing a $250,000 move from the taxable brokerage into a ten-year surrender FIA with a 6.5% annual cap, 0% floor, 100% participation, and no base-contract fee. An optional lifetime-income rider would cost 1% a year if they add it later.

How the comparison numbers were built. Both paths start at $250,000 on the same date and run ten years with no additions and no withdrawals. The brokerage path assumes a constant 7% pretax compound annual return before any capital-gains tax on realized gains. That 7% is an assumption, not a forecast and not the historical average of any specific fund. At 7% the pretax ending value is about $492,000. The annuity path assumes the same starting premium, annual reset, a cap that stays at 6.5% for all ten years, a 0% floor, and a blended credited rate of 4% per year. At 4% the ending account value is about $370,000. The 4% figure is not a guarantee. It is a simplified stand-in for a mixed decade in which some years hit the cap, some years credit a partial gain, and some years credit zero. No rider fee is deducted in that 4% path. Taxes on the brokerage side are not subtracted from the $492,000 figure; annuity growth is tax-deferred and later withdrawals of gain are ordinary income. Neither path models dividends, sequence of returns year by year, rebalancing, inflation, or surrender charges.

Those figures are hypothetical. They were not achieved in any client account. A constant 7% equity path never happens. A constant 4% credited rate never happens either. Caps, participation rates, and spreads can be reset on each anniversary, often down to a contractual minimum far below the initial cap. A ten-year illustration that holds the opening cap fixed overstates what many contracts have historically credited. Early withdrawals above the free-withdrawal amount, commonly around 10% a year, can face surrender charges that start near 9% and a market-value adjustment. Using a single ending-value comparison to decide whether to buy the product ignores liquidity needs, the kids’ college cash-flow, and the fact that the taxable account can be sold in pieces without a surrender schedule.

The product can still have a job. If the couple wants a slice of capital that cannot print a negative calendar-year return while they keep most of the brokerage in equities, the floor is the feature they are paying for. It is closer to a bond substitute with a call option bolted on than it is to a stock fund. It does not replace the 401(k)s. It does not solve college funding. It does not create a legacy unless they later annuitize or add a death-benefit rider and accept the cost.

It is a poor fit if they may need that $250,000 inside seven to ten years, if they are still in peak savings years and can tolerate drawdowns, or if they are buying it mainly for an income rider they have not priced. A frequent mistake is treating the sales illustration’s “what if the index does X every year” path as something the contract will do. Another is adding the rider on day one and letting the 1% fee grind the account for a decade before income starts.

What to look at next is the current cap sheet for the exact product, the guaranteed minimum cap in the contract, the insurer’s actual credited rates on that same strategy over the last ten years, surrender schedule, MVA rules, and AM Best or equivalent rating. Run the same $250,000 against a mix of intermediate Treasuries and a broad index fund using the household’s real tax lot and time horizon. Then decide whether the zero floor on this slice is worth the cap.

The dollar paths above are illustrations built on the assumptions stated in this piece. They are not a recommendation for any household and are not a record of results anyone has earned.