Buffer and Defined Outcome ETFs

How buffered ETFs use options to shape returns over a set period, what the buffer and the cap mean, and what to understand before using one.

By Adam Patti, Chief Executive Officer, VistaShares | Updated November 2026

A buffer ETF uses options to seek a defined range of outcomes over a set period. It aims to absorb a specified portion of an index's losses, the buffer, and in exchange typically gives up gains above a set level, the cap. Buffer ETFs are also called buffered ETFs or defined outcome ETFs.

The buffer is not a guarantee. It applies over the fund's outcome period, under the market conditions in place when its options are set, and losses beyond the buffer remain. The first buffer ETFs came to market in 2018.

What sets the cap?

The fund pays for the buffer by selling upside. When the put options it buys cost more, typically when expected volatility is high, the fund must sell more upside and the cap is lower; when they cost less, the cap can be higher. Interest rates and the dividends of the reference index also play a part.

How do outcome periods work?

Many buffer ETFs use a 12-month outcome period and launch a series of funds, one for each start month. Others reset more often, for example monthly. A shorter period resets the buffer and the upside terms more frequently.

Try it

See how a buffer and a cap shape the outcome

Index return over the outcome period-20% Buffer Cap

Index-20%

Buffered outcome-10%

Hypothetical illustration of a single outcome period with a standard buffer and cap, before fees and expenses, held for the full period. Not the terms or performance of any fund. A buffer reduces, but does not eliminate, losses.

Visual guide

How a buffer is built from options

Simplified, hypothetical payoff at the end of one outcome period, with a 10% buffer and a 12% cap, before fees, expenses and option premiums. Not the terms of any fund.

Visual guide

The whole payoff at a glance

Buffer Cap Losses beyond the buffer

Gray: the index. Purple: the buffered outcome over one full outcome period.

Hypothetical illustration before fees and expenses, held for the full outcome period. Not the terms or performance of any fund. A buffer reduces, but does not eliminate, losses.

Buying partway through

What changes when you buy mid-period

A buffer and cap are set against prices on the first day of the outcome period. Buy later, and the buffer and cap you receive depend on how far the index and the fund have moved since then.

Buffer Cap

Index since period start+5% Fund since period start+3%

Gain left before the cap

Index drop before the buffer starts

Buffer left, from today

Gray: buying on day one. Purple: buying today, at the prices above.

Hypothetical illustration of a simplified buffer held to the end of the outcome period, before fees and expenses. During the period a buffer ETF's price does not move one-for-one with the index, so use the fund's own published figures for its current remaining buffer and cap. Not the terms or performance of any fund.

Why it matters

Large losses need larger gains to recover

Loss-20%

Loss

-20%

Gain needed to get back to even

+25%

$100,000 becomes

$80,000

Simple arithmetic: recovering from a loss of L requires a gain of L divided by (1 minus L). Ignores fees, taxes and contributions or withdrawals.

Read the guides

Articles in this guide

How Do Buffer ETFs Work?

Buffer ETFs use options to seek a defined range of outcomes over a set period, reducing losses up to a buffer in exchange for a cap...

Buffer and Defined Outcome ETFs

What sets the cap?

How do outcome periods work?

See how a buffer and a cap shape the outcome

How a buffer is built from options

The whole payoff at a glance

What changes when you buy mid-period

Large losses need larger gains to recover

Articles in this guide

How Do Buffer ETFs Work?

Buffer ETF Terms Explained: Buffer, Cap, Participation Rate, Outcome Period and Reset

How Is a Buffer Built With Options? A Step-by-Step Look

What Are FLEX Options, and Why Do Buffer ETFs Use Them?

Buffer ETF Myths vs Facts: 10 Common Misconceptions

How Do You Choose a Buffer ETF?

Annual vs Monthly Outcome Periods: How Does Reset Frequency Change a Buffer ETF?

What Drives a Buffer ETF’s Cap?

What Happens When the Index Rises Past a Buffer ETF’s Cap?

Why Doesn’t a Buffer ETF’s Price Move One for One With Its Index During the Outcome Period?

Can You Buy a Buffer ETF in the Middle of Its Outcome Period?

Remaining Buffer and Remaining Cap: What Do They Mean and How Are They Calculated?

Buying a Buffer ETF After the Market Has Risen: What Happens to Your Cap and Downside?

Buying a Buffer ETF After the Market Has Fallen: What Happens When Part of the Buffer Is Already Used?

Why Does a Buffer ETF’s Price Not Move One for One With the Index During the Period?

Where Can You Find a Buffer ETF’s Current Remaining Buffer and Cap?

How Do Monthly Buffer ETF Series Create More Entry Points?

How Does Laddering Buffer ETFs Across Outcome Periods Work?

What Happens at a Buffer ETF’s Reset Date?

What Happens When You Hold a Buffer ETF for More Than One Outcome Period?

How Do You Trade Buffer ETFs? Spreads, Liquidity, Intraday Value and Order Types

Where Can Buffer ETFs Fit in a Portfolio?

How Often Do Stocks Fall? What History Says About the Frequency and Size of Losses

What Are 100% Buffer ETFs, and What Are the Trade-Offs?

Beyond the Standard Buffer: How Do Floors, Dual Directional and Accelerated Designs Work?

Buffer ETFs vs Annuities vs Structured Notes: How Do They Compare?

Covered Call vs Buffer ETFs: How Do the Two Option Strategies Differ?

Deep Buffer ETFs: What Changes When the Buffer Is Larger?

Buffer ETFs vs. Bonds: Which Fits a Portfolio’s Defensive Sleeve?

Buffer ETFs vs. Cash and Treasury Bills: How Do They Compare?

Hedged Equity vs. Buffer ETFs: What Is the Difference?

Buffer ETFs on the S&P 500 vs. the Nasdaq-100: What Changes?

Buffer ETFs vs. Stop-Loss Orders: What Is the Difference?

Buffer ETFs vs. Buying Put Options Yourself: What Is the Difference?

100% Buffer ETFs vs. Treasury Bills: What Is the Difference?

Buffer ETFs vs. Fixed Indexed Annuities: What Is the Difference?

Buffer ETFs vs. Low-Volatility ETFs: What Is the Difference?

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