@anon88017 No, an annuity is just a fixed set of payments set over a period of time (often the remainder of someone's life). An indexed annuity is tied so some outside index, say the S&P500. If the market goes up significantly, the annuitant can receive increased payments, but there is often a cap. Similarly, there is often a floor, usually set at zero, which means that the annuitant cannot lose money.
When you invest in an equity index fund, there is no cap and no floor so the potential for gain is higher, but the potential for loss is greater as well. With an indexed annuity, your upside and downside risks are contained.