BlackRock filed a new bitcoin fund with the SEC on Monday 19 October 2026. It is called the iShares Bitcoin Managed Protection ETF, ticker PBIT, and it arrived as Post-Effective Amendment No. 2,895 to the iShares Trust registration statement, effective 75 days after filing, which puts it on the shelf around 2 January 2027. The wires picked it up this morning and described it the way the filing describes itself: a bitcoin fund that uses options to limit potential losses and limit potential gains.
That description is accurate. It is also, read slowly, the entire story, because across roughly 112,000 words of registration statement the filing never improves on it. There is no cap. There is no floor. There is no period. The document that registers this product with a federal regulator contains, by design and not by omission, not one number that tells you what the protection is or what it costs you in upside. I read the whole thing looking for one.
TL;DR
- BlackRock filed the iShares Bitcoin Managed Protection ETF (
PBIT) on 19 October 2026. It buys call spreads on IBIT in three overlapping monthly tranches and holds no bitcoin at all. - The prospectus states the Floor as “approximately 10%” at the moment a tranche is struck, then says in terms that “the Fund does not provide a fixed Tranche Protection Start Value, Floor or Tranche Cap Value” and that it has “broad discretion to increase or decrease” that value “at any time”.
- I rebuilt the three-tranche ladder on six months of real bitcoin prices. On 20 October 2026 the three live strikes sit 10.00%, 10.23% and 23.43% below spot. Across 119 simulated days the blended gap had a median of 16.27% and a maximum of 23.72%. Only 6 of those 119 days landed anywhere near the advertised 10%.
- Ten days earlier, Calamos filed a bitcoin protection ETF of its own with a Cap of 36.22%, a Floor of 20%, an Outcome Period running 7 October 2026 to 31 October 2027 and a 0.69% fee, all printed in the summary prospectus. Same asset, same month, same options machinery, numbers committed.
- A provably fair draw against a payout schedule the house can re-cut monthly is a very precise proof of the wrong half. Satoshie fixes ticket price, entry cap and prize structure in the deployed contract before entries open, which is a narrower claim than it sounds and the only one we can actually make.
Two defined terms and five uses of “broad discretion”
The mechanics are not complicated. For each tranche the fund buys an in-the-money call on IBIT and sells an out-of-the-money call on IBIT, both as FLEX options, and parks the rest in short-dated fixed income to throw off interest that helps pay for the structure. The bought call’s strike is the Tranche Protection Start Value. The sold call’s strike is the Tranche Cap Value. Below the first, you own nothing and therefore cannot lose any more. Above the second, bitcoin can do what it likes and you do not get it.
Here is the filing’s own account of the first one, quoted exactly:
“With respect to each tranche, the Tranche Protection Start Value typically is set at approximately 90% of the value of the Bitcoin Reference Asset at the time the purchased Bitcoin Options are acquired, which establishes an initial maximum loss exposure to the Bitcoin Reference Asset for that tranche of approximately 10% (referred to as the ‘Floor’), before taking into account fees and expenses as of the date acquired.”
Count the qualifiers: typically, approximately, approximately, initial, for that tranche, before taking into account fees. Six hedges around one number, and the number is the headline. The very next sentence removes it anyway:
“However, the Fund has broad discretion to increase or decrease the Tranche Protection Start Value for one or more tranches at any time.”
The cap gets the same treatment. Its strike “is determined based on prevailing market conditions at the start of the applicable tranche, and the Fund has broad discretion as to whether and when it sells Bitcoin Options”. So the ceiling on your upside is whatever the options market happens to pay on a day you did not pick, assuming the fund chooses to sell at all.
And then the summary of principal risks says the quiet part at normal volume:
“Because the tranches have staggered start dates and the Fund has broad discretion to hold more or fewer tranches, to use Bitcoin Options with varying expiration dates and strike prices, and to set or adjust the Tranche Protection Start Value and Tranche Cap Value for each tranche, the Fund does not provide a fixed Tranche Protection Start Value, Floor or Tranche Cap Value.”
That is not a risk disclosure in the usual sense. A risk disclosure tells you a promise might fail. This one tells you there was never a promise with a number in it. The phrase “broad discretion” appears five times in the document and “discretion” thirty-five. “No assurance” appears sixteen times. I am not quoting these to be snide about legal boilerplate, which every fund has. I am quoting them because in this particular product the discretion is not a safety valve around a committed term. It is the term.
The blanks that are normal, and the one that is not
Be fair to BlackRock about one thing, because the cheap version of this post is available and it is wrong. The fee table in this filing reads “Management Fee ____%” and “Total Annual Fund Operating Expenses ____%”, and the expense example reads “$____”. That is completely normal. A 485APOS is a pre-effective amendment; pricing goes in later, in the 485BPOS, before anyone can buy a share. Ninety-nine blanks in a document at this stage means the document is at this stage. It does not mean anything else and I am not going to pretend it does.
The structural absence is the one that will still be there on launch day. The fee will be filled in. The Floor will not, because the filing says there is no fixed Floor to fill in. The Cap will not, because the Cap is reset every month per tranche at whatever the FLEX market pays. What you will get instead is a web page: “Information regarding the Fund’s tranches, including the Tranche Cap Values, Tranche Protection Start Values, tranche weights and the Fund’s current holdings, is available at www.iShares.com”, which the filing immediately qualifies as information that “does not represent a specific outcome for any investor due to the Fund’s overlapping tranches, and is subject to change”.
Read that twice. The disclosure the fund offers in place of a committed number is a page that explicitly declines to tell you your own terms.
The floor is measured from a moment you did not choose
Here is the mechanical consequence, and it is stated in the filing rather than inferred by me:
“After a tranche begins, increases in the Bitcoin Reference Asset will cause the current loss potential for that tranche to exceed the Floor before any protection applies.”
A tranche struck when bitcoin was at 70,000 protects from 63,000 down. If bitcoin is at 82,000 when you buy your shares, that tranche does not protect you from 10% below 82,000. It protects you from 23% below 82,000. The first 23% of your decline is entirely yours, and the fund’s headline number never changes, because the headline number was never about you. It was about a tranche, on its birthday, before fees.
Everyone who has ever read a defined-outcome fund factsheet knows this shape. What is different here is that there is no outcome period to hold to, no reset date you can plan around, and no single strike you could have matched by buying on the right day. There are three ladders running at once, each anchored to a different past price, re-cut every month, in weights the fund chooses. There is no day on which you can buy this fund and receive the advertised 10%.
So I built the ladder
Nobody has run this arithmetic, as far as I can find, so I ran it. I took daily bitcoin closes from 24 April to 20 October 2026, assumed the structure the filing describes (three tranches, monthly stagger over a calendar quarter, each struck at 90% of the reference price on its start date, equal weights) and asked one question for every day in the sample: how far would bitcoin have to fall from today’s price before the blended protection start value is reached?
That distance is the honest version of the Floor. It is what you are exposed to, measured from where you actually bought.
Today, 20 October 2026, with bitcoin at $81,448.19:
| Tranche struck | Bitcoin that day | Protection start (90%) | Distance below today’s price |
|---|---|---|---|
| 20 October 2026 | $81,448.19 | $73,303.37 | 10.00% |
| 20 September 2026 | $81,236.41 | $73,112.77 | 10.23% |
| 20 August 2026 | $69,291.01 | $62,361.91 | 23.43% |
| Blended | $69,592.68 | 14.56% |
One of the three tranches holding your money today begins protecting 23.43% below the price on the screen. It is not broken and nobody did anything wrong. Bitcoin ran 17.5% between two tranche start dates, and a strike set in August is a fact about August.
Now the full sample, 119 days on which a three-tranche ladder would have been fully populated:
| Measure | Blended distance to protection |
|---|---|
| Advertised Floor | approximately 10% |
| Median across 119 days | 16.27% |
| Mean | 12.47% |
| Worst day (28 August 2026) | 23.72% |
| Days between 9% and 11% | 6 of 119 |
| Days worse than 10% | 71 of 119 |
| Days worse than 20% | 30 of 119 |
| Days bitcoin was already below the blended strike | 10 of 119 |
Six days out of 119. That is how often this ladder would have offered something recognisable as the number in the prospectus. The median investor day was 16.27%, which is 63% more unprotected downside than the figure the product is named after.
The last row is the other half of the same coin and it cuts the opposite way. On ten days bitcoin had already fallen through all three strikes. On those days you are not exposed to a further 16%, because the spreads are already worth almost nothing and the loss has happened. What you have instead is a fund that will only participate in the recovery once bitcoin climbs back through strikes set months ago, while new tranches re-cut lower underneath. Protection and participation are the same instrument viewed from different sides, and the ladder gives you less of both at exactly the moments you notice.
Somebody else filed the same product with the numbers in it
This is the part that decides whether the post is a complaint about financial products in general or an observation about this one. If committing to the numbers were impossible for a bitcoin protection fund, the absence would be the asset’s fault and there would be nothing to write.
Ten days before BlackRock’s filing, on 9 October 2026, Calamos filed the summary prospectus for the Calamos Bitcoin 80 Series Structured Alt Protection ETF. Same asset class. Same month. Same machinery, down to using FLEX options on IBIT among other bitcoin ETPs. Here is what its summary prospectus says, on page one, in the investment objective:
“For the Outcome Period beginning on October 7, 2026 through October 31, 2027, the Cap is 36.22% and the Floor is 20%. When the Fund’s total fund operating fees and expenses are taken into account, the Cap is 35.53% and the Floor is 20.69%.”
A cap to two decimal places. A floor to two decimal places. Both restated net of fees, because the honest version of a capped product tells you what the fee does to the cap. A stated period with a start date and an end date. A management fee of 0.69%, printed. Every one of those commits the issuer to something checkable on a date certain.
iShares PBIT |
Calamos Bitcoin 80 Series | |
|---|---|---|
| Filed | 19 October 2026 | 9 October 2026 |
| Upside cap | not stated, reset per tranche | 36.22% (35.53% net) |
| Downside floor | “approximately 10%” at tranche start, adjustable at any time | 20% (20.69% net) |
| Defined period | none | 7 Oct 2026 to 31 Oct 2027 |
| Management fee | blank (pre-effective) | 0.69% |
So it is a choice. Not a limitation of options, not a limitation of bitcoin, not a limitation of the 1940 Act. One issuer decided the terms of the deal belong in the document and the other decided they belong on a website, revisable monthly, at the manager’s discretion.
I want to be careful here, because the managed version is not obviously worse as an investment. A ladder that re-strikes every month adapts; a fixed buffer struck in October 2026 is stuck with October 2026 whatever happens. In a long drawdown the managed structure can genuinely do better, and anyone telling you otherwise is selling something. The two products differ on verifiability, not on expected return, and those are separate arguments that get fused constantly.
Why this is a fairness question and not a finance question
Translate PBIT into the language of this blog and the shape is instantly familiar. A house offers you a game. The maximum you can win is set by the house at a moment of its choosing, from conditions you cannot observe, and reset monthly. The maximum you can lose is also set by the house, is described as “approximately” a number, and can be moved “at any time”. The current values are published on a page that says they do not represent your outcome and are subject to change. Every individual draw is run correctly.
Would you call that game fair? The outcomes might be perfectly honest. The randomness might be impeccable. The question nobody asks is whether honest execution of undisclosed terms is a thing worth proving, and the answer is that it is exactly half of a thing.
We have made this argument in the other direction before, and it is worth being precise about what is new, because the series has circled this ground.
It is not the 2x ETF problem, where a fund keeps an exactly stated promise about one day and the entire industry reads it as a promise about a month. That fund’s disclosure was true, complete and arithmetically checkable the moment you read it. Here there is nothing to misread.
It is not the index problem, where the number your contract settles on is somebody’s intellectual property, maintained in confidence, licensed with an expiry date. An index is at least published, continuously, to everybody, on the same terms. A tranche cap set privately each month is not an index, it is a parameter.
It is not the computed-balance problem, where a prize pool you read off-chain is a function call whose answer drifts because the token rebases. That number changes according to a formula anyone can run. This one changes according to a decision nobody sees.
And it is not the repackaging complaint we made about this same issuer in June, when it sold IBIT shares and launched a covered-call bitcoin fund the same week. That post was about wrappers and fees. This is not a wrapper objection. PBIT is a genuinely different payoff from IBIT and from an income fund, and it may well be useful to people who want bitcoin exposure they can hold without checking their phone at 3am. The objection is narrower and harder to wave away: the payoff has no stated shape.
What Satoshie fixes, and what it does not
The claim we make is deliberately small, and this is the week to restate it precisely. On a Satoshie raffle the ticket price, the entry cap and the prize structure are written into the contract that is deployed before entries open, and they are fixed there for the life of that draw. The VRF coordinator and the oracle key that will answer the draw are named in public code before anyone stakes anything. The proof is verified on-chain before the payout callback is permitted to act. No admin key can reassign a result after the fact.
Notice what that is not. It is not a claim that our terms are better than a fund’s, or that a 10% floor is a bad deal, or that discretion is sinister. Somebody at Satoshie chooses the ticket price and the prize. A human sets those numbers using judgment, same as a portfolio manager sets a strike. The difference is only this: we choose them, publish them in the contract, and then cannot move them while you are inside the draw. Choosing and publishing is not the same as not choosing.
And we have form for measuring our own mutable surface rather than claiming we have none. On 13 October we found that four of nine keys on a multisig could reprice every VRF draw on Base, and on 17 October that only 2 of 59 Base game contracts cannot swap their randomness oracle after players have entered. Both of those are our side of the fence and both are uncomfortable. The reason we publish them is that a platform which has never named a single thing it can change is making the PBIT move with better branding.
Honest limits
Six, and they matter.
First, my ladder is a simulation, not a holding. I used spot bitcoin daily closes from one vendor as a stand-in for IBIT, which tracks the CME CF Bitcoin Reference Rate New York Variant and will not be identical. The fund buys options on IBIT, not on spot, so the strikes it actually sets will differ from mine.
Second, I assumed equal weights across the three tranches. The filing says weights vary and will be published. A ladder weighted towards its newest tranche would show a tighter distance to protection than mine, and one weighted the other way would show worse.
Third, the 90% strike and the monthly stagger come from the word “typically” in a document that reserves broad discretion to do otherwise. My sample describes the structure as described, not the fund as it will be run.
Fourth, 119 days is six months of one asset, covering a run from roughly $60,000 to $82,000. A quieter market produces a tighter spread between tranches and a result much closer to the advertised 10%. The gap I measured is a function of bitcoin’s volatility, which is rather the point, but it is not a constant.
Fifth, the blank numbers in a 485APOS are routine and I have said so twice because the temptation to pretend otherwise is strong.
Sixth, nobody here has done anything wrong, and the fund has not launched. Every sentence I quoted is a sentence BlackRock wrote and filed voluntarily, which is more candour than most structured products offer. The complaint is not that the disclosure is bad. The complaint is that the disclosure is excellent and what it discloses is that there are no terms.
Three questions
If you hold a product that promises to limit your losses, ask these.
From what price? Protection quoted as a percentage is meaningless without the level it is measured from and the date that level was set. If the answer is “it depends which tranche”, you do not have a floor, you have an average of three.
Who can move it, and do I find out before or after? There is a real difference between a number that changes on a published schedule and a number that changes when someone decides. Both are called “managed”.
What am I giving up, in numbers, and when was that decided? Every floor is paid for with a ceiling. If the ceiling has no figure attached, you have agreed to a price you have not been quoted.
Ask the third one of us too. Our answer is a contract address and a block number, which is not a virtue, just a format that makes lying expensive.
This is the one hundred and first unasked half of fairness.
📷 Photo by Angèle Kamp (@angelekamp) on Unsplash
