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

By Adam Patti, Chief Executive Officer, VistaShares | Published November 13, 2026

Remaining cap and remaining buffer describe what a buffer ETF offers an investor who buys today, measured from the fund’s current price to the end of its outcome period. The remaining cap is the gain left before the fund reaches its cap, and the remaining buffer is how much loss the buffer can still absorb, measured from today’s index level, and it is paired with a third figure: how far the index can fall before the buffer starts. These figures change every day as the index and the fund move.

Why are “remaining” figures needed?

A buffer ETF publishes a buffer and cap at the start of each outcome period. Those terms are measured from the reference index’s level on the first day to its level on the last day, and they describe the outcome for an investor who holds for the full period. Our article on buffer ETF terms explains them.

Once the period is underway, the index and the fund move. An investor buying on a later date pays the current price and starts from the current index level, so the original terms no longer describe that investor’s potential outcome. Remaining figures restate the terms from today’s starting point.¹ Our article on buying a buffer ETF mid-period explains why this matters.

What is the remaining cap?

The remaining cap, sometimes called the gain left before the cap, is the maximum return an investor buying today could receive by the end of the outcome period, before fees, if the fund reaches its cap.

Formula: Gain left before the cap = (1 + cap) ÷ (1 + fund change since period start) minus 1

The fund’s change is used, rather than the index’s, because the investor’s return depends on the price paid for the fund. If the fund is up since the start, the remaining cap is smaller than the original cap. If the fund is down, the remaining cap is larger.

Example: with a 12% cap and the fund up 3% since the period began, the gain left before the cap is 1.12 ÷ 1.03 minus 1, or about 8.7%. (Hypothetical, before fees and expenses.)

What is the remaining buffer?

The remaining buffer is the amount of further decline the buffer can absorb, measured from today’s index level.

Formula when the index is up from its start: Buffer left from today = buffer ÷ (1 + index change)

Formula when the index is down from its start: Buffer left from today = (index change + buffer) ÷ (1 + index change), with zero as the floor

The remaining buffer is measured using the index’s change, because the buffer is defined by the index’s level relative to its starting point.

Example with the index up: with a 10% buffer and the index up 5%, the buffer left is 10% ÷ 1.05, or about 9.5%. (Hypothetical, before fees and expenses.)

Example with the index down: with a 10% buffer and the index down 4%, the buffer left is (-4% + 10%) ÷ 0.96, or about 6.3%. Part of the buffer has already been used. (Hypothetical, before fees and expenses.)

If the index has fallen by more than the full buffer, the remaining buffer is zero, and further declines pass through to the investor.

What is the index drop before the buffer starts?

When the index is above its starting level, there is a stretch of decline that the buffer does not cover: the index must first fall back to its starting level.

Formula: Index drop before the buffer starts = 1 ÷ (1 + index change) minus 1

Example: with the index up 5%, the index drop before the buffer starts is 1 ÷ 1.05 minus 1, or about -4.8%. An investor buying today would bear that decline before the buffer begins. (Hypothetical, before fees and expenses.)

When the index is at or below its starting level, this figure is zero, because the buffer is already in effect.

How do the three numbers fit together?

Using the series’ worked example, a fund with a 10% buffer and a 12% cap, with the index up 5% and the fund up 3% since the start, offers a new investor about 8.7% of gain left before the cap, a 4.8% index drop before the buffer starts and about 9.5% of buffer left, measured from today. (Hypothetical, before fees and expenses.)

In words: from today’s price, the investor can gain up to about 8.7%; if the index falls, the first 4.8% of decline is not covered; the buffer then absorbs roughly the next 9.5%; and any decline beyond that passes through.

You can try these numbers yourself with the “What changes when you buy mid-period” calculator on our buffer ETF guide page.

Why might published figures differ slightly from these formulas?

Issuers may calculate remaining figures using net asset value or market price, may include or exclude fees and may use different timing conventions, such as the prior day’s close. The underlying logic is the same, but small differences are normal. Investors should check how each issuer defines its figures. Our article on where to find a buffer ETF’s remaining buffer and cap covers this.

What do these figures not tell you?

They describe the potential outcome at the end of the outcome period, before fees. They do not predict where the index ends, and they do not describe the fund’s value on any day before the end. During the period, the fund’s price reflects the current value of its options. Our article on why a buffer ETF’s price does not move one for one with the index explains this. Our overview of how buffer ETFs work provides more background.

Investments involve risk, including possible loss of principal.

Frequently asked questions

What is the remaining cap on a buffer ETF?

It is the maximum gain an investor buying today could receive by the end of the outcome period, before fees, if the fund reaches its cap. It equals one plus the cap, divided by one plus the fund’s change since the period started, minus one.

What is the remaining buffer?

It is the amount of further index decline the buffer can absorb, measured from today’s index level. When the index is up, it equals the buffer divided by one plus the index change. When the index is down, part of the buffer is used, and the remaining amount is smaller.

Why does the remaining cap use the fund’s change but the buffer uses the index’s change?

An investor’s return depends on the price paid for the fund, so the remaining cap uses the fund’s change. The buffer is defined by the index’s level relative to its starting point, so the remaining buffer and the index drop before the buffer starts use the index’s change.

Can the remaining cap be higher than the original cap?

Yes. If the fund has fallen since the period started, an investor buying at the lower price has more room to gain before the fund reaches its cap. In that case, part of the buffer may already be used, which the remaining buffer figure shows.

What happens when the remaining buffer reaches zero?

If the index has fallen by more than the full buffer since the period started, the remaining buffer is zero. Further declines pass through to the investor until the end of the period, although the remaining cap may be substantial.

How often do these figures change?

Every trading day, as the index and the fund’s price move. Many issuers update them daily on their websites, typically as of the prior market close. Investors can recalculate them with current figures using the calculator on our buffer ETF guide page.

Cite this page: Adam Patti, "Remaining Buffer and Remaining Cap: What Do They Mean and How Are They Calculated?," VistaShares, updated November 13, 2026, https://www.vistashares.com/remaining-buffer-and-remaining-cap/. Plain-text version.

This material is provided for educational purposes only. It is not investment, legal or tax advice, and it is not a recommendation or an offer to buy or sell any security. Information is drawn from sources believed to be reliable as of the date of publication, is not guaranteed as to accuracy or completeness, and may change without notice. Figures attributed to third parties are their estimates. Projections and forecasts are not guarantees of future results. Investors should consult their own financial, legal and tax professionals before making investment decisions. Investments involve risk, including possible loss of principal. Strategies that use options involve additional risks, including limited participation in market gains, the risk that options do not perform as intended, and changes in distributions. Tax treatment depends on individual circumstances and on current law, which may change.