Explainers

Spot vs futures Bitcoin ETFs: where the money leaks

Spot Bitcoin ETFs hold bitcoin; futures funds hold expiring contracts. We work through roll cost with real numbers and show why the gap reached an estimated 2.9% a year.

Between October 2021 and January 2024, if you wanted bitcoin exposure through a US brokerage account, one option existed: a futures fund. Millions of dollars went into those products because they were the only door open. Then spot funds arrived and the futures route became, for almost every long-term purpose, an expensive mistake.

The reason is a mechanism most buyers never see on a statement. It is worth understanding properly, because the same logic applies to commodity funds generally and it explains why two products tracking the identical asset can diverge by two percentage points a year.

The core difference in one paragraph

A spot fund buys bitcoin and holds it. Nothing expires, nothing needs replacing, and the only ongoing cost is the sponsor fee. A futures fund buys contracts that oblige delivery or cash settlement on a specific date. Those contracts die on schedule. To keep exposure alive, the fund must sell the expiring contract and buy a later-dated one, over and over, forever.

That perpetual replacement is the whole story. Everything expensive about a futures fund follows from it.

Roll cost, worked through with numbers

Suppose bitcoin trades at $77,000. The futures contract expiring this month also trades near $77,000, because at expiry it must converge on spot. But the contract expiring next month trades at $77,600 — traders will pay a premium for deferred exposure, since holding a futures position frees up capital versus buying the asset outright.

The fund's position is expiring. It sells at $77,000 and buys the next month at $77,600. Bitcoin has not moved a dollar, and the fund now controls slightly less exposure for the same money. That gap — roughly 0.78% in this example — is roll cost. Repeat monthly and it compounds into several percent a year.

The condition where later contracts cost more than nearer ones is called contango, and in crypto it has been the normal state for most of the market's history. The reverse, backwardation, hands the fund a small tailwind instead — but it tends to appear in panics, precisely when you are least likely to be buying.

Side by side

The real-world evidence matches the theory. In the period to March 2026, BITO was down 29.93% while spot bitcoin was down 27.05%. Nearly three percentage points of underperformance, in a falling market, from a product whose whole purpose was to track the thing that fell less.

Why futures funds came first

This ordering was a regulatory artefact, not a market preference. The SEC was willing to approve bitcoin exposure through CME futures — a regulated, surveilled derivatives market with position limits and a clearing house — years before it would approve a fund holding spot bitcoin, whose underlying market it argued was vulnerable to manipulation.

So BITO listed in October 2021 as a 1940 Act fund holding CME contracts, and it worked as designed. The inconsistency eventually became the legal lever that broke the deadlock: Grayscale argued the SEC could not rationally permit a futures-based bitcoin ETF while refusing a spot one, a federal appeals court agreed, and spot approvals followed in January 2024. The full sequence is on the approval timeline.

When a futures fund still makes sense

Rarely, but not never. Three cases hold up.

• Short-horizon trades. Roll cost accrues over months. Over a few days it is negligible, and futures products often carry deep options markets and heavy volume.
• Platform restrictions. Some retirement plans, advisory platforms and non-US brokerages permit 1940 Act registered funds but not 1933 Act commodity trusts. Where that is the constraint, a futures fund may be the only compliant route.
• A view on the curve itself. If you specifically expect backwardation, the roll works for you rather than against you. This is a professional trade, not a retail one.

For a position you intend to hold for a year or more, none of these apply and the spot fund is simply cheaper for identical exposure. The complete BITO breakdown, including its distribution behaviour, is in the BITO profile.

Inverse and leveraged variants: the same problem, amplified

ProShares also runs BITI, targeting -1x the daily performance of bitcoin, and SBIT at -2x. Both use futures and swaps rather than genuinely shorting bitcoin, and both reset daily.

Daily reset means the stated multiple applies to one day only. Hold a -1x product for a month in a choppy market and your return can differ substantially from -1x the month's move — usually for the worse, because volatility decay works against both directions of a leveraged product. ProShares says so plainly in its own materials: these are designed as short-term trading tools, not investments. The mechanics and the decay arithmetic are in how to short a Bitcoin ETF.