Every fixed indexed annuity (FIA) makes you choose what your interest credits are calculated from. The menu almost always includes the S&P 500, and increasingly it's crowded with proprietary indices — custom benchmarks with engineered-sounding names, built by banks or index providers, often exclusively for one insurer.
The choice matters more than most buyers realize, because it decides not just what you might earn but whether you can verify what you're being sold. This article gives you the honest version of the tradeoff. If you're new to the product itself, start with how fixed indexed annuities work, then come back.
The Two Kinds of Indexes on an FIA Menu
Plain benchmarks are the indexes you already know — the S&P 500 above all, sometimes the Nasdaq-100 or Russell 2000. They have decades of live, publicly quoted history, and everyone from the insurer to your neighbor computes them the same way. Because these indexes are volatile, the insurer bounds your credit with a cap, a participation rate, or a performance trigger — the levers explained in our guide to FIA cap rates.
Proprietary indices — also sold as custom, engineered, or hybrid indices — are built to be put inside insurance products. Most are volatility-controlled: the index automatically moves money between an equity component and cash or bonds to keep its measured volatility near a stated target. Many are also "excess return" constructions, meaning a cash or financing rate is subtracted from performance before anything is credited to you.
Why Volatility Control Exists
An insurer funds your index credits by spending an options budget — the interest thrown off by its bond portfolio — on options tied to your chosen index. Options on a calm index are cheap; options on a volatile one are expensive. By engineering the volatility down, the insurer can afford far more notional upside per budget dollar, which is why proprietary-index strategies are so often quoted with high, uncapped participation rates while the S&P 500 strategy next to them carries a modest cap.
That's not a trick by itself — it's the same economics either way. The catch is where the risk moves. A volatility-controlled index protects its own stability by cutting equity exposure when markets get turbulent. Turbulence is exactly when sharp rebounds happen, so these indexes routinely sit underexposed through the strongest recovery days. A high participation rate applied to a muted index can credit less than a low cap applied to a benchmark that captured the rebound.
S&P 500 vs Proprietary: The Honest Comparison
| What to weigh | S&P 500 point-to-point | Volatility-controlled proprietary index |
|---|---|---|
| Transparency | Public, quoted everywhere, computed identically by everyone | Methodology in a rulebook few read; daily level published but hard to sanity-check |
| Track record | Decades of live history through every kind of market | Often only a few years live; earlier performance is usually a backtest |
| Typical crediting structure | Cap, participation rate, or performance trigger | High or uncapped participation rate, sometimes with a spread |
| What limits your upside | The declared cap or participation rate | The index's own volatility targeting, plus any embedded deduction, plus the declared rate |
| Behavior in sharp rebounds | Full index move measured; credit bounded by the declared rate | Often underexposed during the rebound because volatility was recently high |
| Comparison shopping | Directly comparable across carriers on live tables | Usually exclusive to one carrier, so no apples-to-apples comparison exists |
One row of that table deserves emphasis: the construction of the index itself. A price-return S&P 500 strategy already excludes dividends. Many proprietary indices go further — an excess-return version subtracts a cash rate from performance, and some apply a fixed daily deduction on top. Two strategies quoting the same participation rate can be measuring meaningfully different things, and the differences all run in the insurer's favor.
Backtests Are Not Track Records
Many proprietary indices were launched only recently, yet their marketing sheets show smooth performance lines running back a decade or more. Everything before the live date is hypothetical — computed after the fact, with rules chosen by people who already knew what markets had done. Backtests systematically flatter the strategy; regulators have repeatedly warned about exactly this pattern in indexed-product marketing.
Before allocating to a custom index, ask three questions: When did the index go live? What has it returned since that date — not before it? And is it a price-return, total-return, or excess-return construction? If your agent can't answer all three, that tells you something too.
Why Carriers Lead With Custom Indices
Three reasons, none of them sinister but all worth knowing. First, high uncapped participation rates make better headlines than modest caps, and volatility control makes them affordable to offer. Second, exclusivity blocks comparison shopping — nobody can undercut a rate on an index only one carrier offers. Third, the declared rates on every strategy reset at renewal, and opaque strategies make weak renewals harder to spot. That last risk applies to S&P 500 strategies too, and it's big enough to deserve its own explainer: why FIA caps drop after year one and how to vet carriers.
A Sensible Way to Choose
- Start with what you can verify. Put a core allocation in an S&P 500 strategy whose terms you can benchmark against live data — today's leaders are ranked on the FIA cap rate table, with companion tables for participation rates and performance trigger rates, all sourced from CANNEX.
- Use proprietary strategies as a diversifier, not the core. Different crediting engines pay off in different market paths; splitting allocations means one bad path doesn't zero your whole year.
- Demand the live inception date and since-live performance for any custom index, in writing, before allocating to it.
- Remember what the index choice can't change. Every FIA strategy sits on the same 0% floor — index losses don't reduce your credited value, whichever index you track. How that floor compares with RILA buffers is covered in floor vs buffer protection.
- Reallocate deliberately at each anniversary. Renewal terms on every strategy are re-declared each period; market-wide movements show up on the annuity rate changes tracker.
The index question is ultimately a transparency question. A plain S&P 500 strategy tells you exactly what game you're playing and lets you check the score. A proprietary index asks for more trust — in the index designer, in the backtest, and in the carrier's renewal behavior. Give that trust deliberately, in measured amounts, or not at all.
Free Comparison Report
Compare live FIA crediting rates by strategy
S&P 500 caps, participation rates, and performance triggers ranked from highest to lowest, with carrier and AM Best rating shown for each — sourced from CANNEX and updated as carriers move.