FBR and sFBR
A fixed supply distributed for using the protocol, what staking it does and what it costs to stop, and the four ways it divides a flow between users without creating one.
Spec v0.9.1, reviewed 2026-09-08
FBR is Fyber's token. It has a fixed supply of 100,000,000 FBR, minted once at deployment toward contracts nobody owns. It is not sold: no offering, no auction, no company. It is distributed to the people who use the protocol, by seasons, on a curve written into the code.
Guarantee
No regime, threshold, ceiling, rate or activation criterion anywhere in the protocol reads FBR. The yield of sfyUSD contains no emission. If FBR went to zero tonight, a borrower's threshold, a depositor's interest and the peg would be exactly where they are.
Rules R-19.12.1, invariant 52
Where the supply goes
| Share | Amount | Where it sits at deployment | When it moves |
|---|---|---|---|
| 47% | 47M | The distributor | Season by season, on the curve |
| 21% | 21,000,000 FBR | Staked by the protocol itself | Never withdrawn; seized alongside every other lot when there is bad debt |
| 20% | 20M | Vesting contracts, one per address | A cliff a year after the first season, then three years linear |
| 10% | 10M | A vote contract | Only if an election names someone to deploy a version 2; otherwise locked for ever |
| 2% | 2,000,000 FBR | The distributor | For everything done before the first season, claimable at once |
Rule R-19.7.1
The seasons
The first season opens 180 days after deployment. Each lasts 90 days. Anyone may close a finished season; nobody can open one early or skip one.
Four things earn counters, and each has its share of the season's budget:
| Class | What it counts | Share |
|---|---|---|
| Depositors | fyUSD-days in a Stability Pool or in sfyUSD | 35% |
| Borrowers | fyUSD of interest actually accrued, at a rate capped by tier | 20% |
| FBR liquidity | In-range liquidity-time in the FBR/fyUSD pool | 15% |
| Vault liquidity | In-range value × time × lock multiplier, per branch | 30% |
A staker's counters are multiplied by up to 1.5×, which is a division of the same budget between users and adds nothing to it. The vault class is the exception: its multiplier is the lock, not the stake.
The borrower class counts accrued interest only, and only up to 3% on tier 1, 5% on tier 2 and 8% on tier 3. Origination and rate-change fees earn nothing. Choosing a rate above the cap pays more to the Stability Pool of your branch and farms no faster, which is worth knowing before you set one.
The budget of a season is fixed by a curve that halves every 912 days, with the first four seasons running steeper than the rest and the tail running shallower. Two ceilings are asserted at deployment and cannot be exceeded by construction: 6.65% of the supply in the first season, and 17.96% across season zero and the first four together.
| Season | Budget |
|---|---|
| 1 | 4,408,000 FBR |
| 2 | 4,117,000 FBR |
| 3 | 3,845,000 FBR |
| 4 | 3,590,000 FBR |
| 5 | 2,053,000 FBR |
That is the shape, and the step from the fourth season to the fifth is 43%. It is a constant of the deployed contract, not a decision anybody takes, and it is written here so that nobody meets it as a surprise. The first year distributes 17,960,000 FBR, the second 7,430,000 FBR, the third 5,650,000 FBR.
Nobody computes any of this by hand. There is no list, no root, no conversion rate and no human act anywhere in the path from using the protocol to holding FBR.
Rules R-19.8.1 to R-19.8.5
Claiming
claim(k) releases a season's allocation as a straight line over 90 days, liquid. claimStaked(k) takes the whole of it straight into the stake instead.
The vault class has no liquid path: it is delivered staked, and it leaves through the exit grid. That makes it free to withdraw 7 days after you claim it.
Staking
Staking creates a dated lot. A lot counts for 25% of its size on the day it is staked and rises to the whole of it over 365 days. A lot a year old therefore weighs four times a lot staked today, per token.
That single weight does five things, and there is no second notion anywhere:
- A share of the protocol's revenue. 10% of the interest flow, rising to 15% over 365 days, plus half the vault fees. It fills the reserve first, and only buys FBR once that reserve holds 2% of the debt.
- A larger share of a Stability Pool's yield, up to 1.50×, saturating at 0.25× of weight per fyUSD deposited.
- A better place in the redemption queue, up to 2%, saturating at 0.10× of weight per fyUSD of debt.
- A multiplier on your season counters, up to 1.5×.
- First loss. Staked FBR is what covers bad debt after the fyUSD reserve. That applies from the first day you stake.
The second, third and fourth divide a flow between users. They create nothing, and a user who holds no FBR receives a smaller share of the same total.
Rules R-19.2.1, R-19.4.1, R-19.10.1, R-19.11.1
What the revenue share actually does
It never arrives as a liquid token. When the reserve is full, the flow buys FBR on the market in hourly tranches, bounded at 25% of the pool's depth, and the purchase is credited into your existing lots, in proportion to your stake, with their dates unchanged. No new lot is created and your average age does not move. The protocol's own lot receives nothing: its share is burned.
The consequence is that a buy-back creates no selling pressure at all inside seven days, because what it credits cannot leave faster than the grid allows.
When it actually starts, and how large it is
The reserve is filled first, and it starts at zero with no source but revenue, so it reaches its target somewhere between the end of the second year and the end of the third. Nothing is bought back before that.
| Year | The buy-back, against what the seasons distribute |
|---|---|
| 1 | About nothing |
| 2 | At most 2% |
| 3 | At most 13% |
| 4 | 27% to 37% |
| 5 | 77% to 105%, so it crosses |
The crossing is in the fifth year, once the team's vesting of 6,670,000 FBR a year from month 12 to month 48 has finished. And for most of that time the buy-back is not even a buy-back for holders: at twelve months the protocol's own lot carries so much of the staking weight that about 90% of every purchase is burned rather than credited to anyone.
Risk
Put plainly: for the first year the buy-back is close to nothing, most of what there is gets burned rather than credited, and the seasons are distributing 17,960,000 FBR. The only mechanical floor under the price of FBR in that period is zero.
Report 11 §6.2
Rules R-19.5.1, R-19.5.2
What leaving costs
requestUnstake removes the amount from your weight immediately and starts a clock. withdraw delivers what the grid leaves.
The fee is a straight line between four points, so there is nothing to time and no hour at which waiting longer is worth nothing.
| You wait | Kept back | You receive |
|---|---|---|
| Nothing | 70% | 30% |
| Twelve hours | 60% | 40% |
| A day | 50% | 50% |
| Two days | 40% | 60% |
| Three days | 30% | 70% |
| Five days | 15% | 85% |
| 7 days | Nothing | All of it |
An hour of waiting is worth 0.83 of a point on the first day, 0.42 up to the third and 0.31 up to the seventh, and everything kept back is credited to the stakers who stayed.
A stake on its way out has a weight of zero: no revenue share, no boost, no shield, no multiplier, no vote. It receives no credits. Its age is frozen. And it can still be seized until you actually withdraw.
cancelUnstake puts it back at any time, dated today. Left more than 7 days past the last step, it returns to the stake through settleExpired, which anyone may call, at no cost. Splitting a withdrawal into a hundred small ones costs exactly the same, because each carries its own clock.
Taking part of your stake out no longer resets the age of the rest. The age falls by the fraction withdrawn, so half a stake withdrawn leaves the other half at half its age. That is what makes the last row of the table true for a partial exit as well as a total one.
Rules R-19.2.4, R-19.2.5, R-19.2.6
The seizure
When a branch carries bad debt that the fyUSD reserve did not cover, anyone may call for a seizure 24 hours later. It takes the same fraction of every staked lot, the protocol's own included and exiting lots included, in no order at all, and puts it in a 24-hour auction whose price rises from zero. Whatever the auction does not sell is returned.
Two ceilings bound it. A branch cannot be seized against twice inside 7 days, and across every branch together no more than 30% of the whole stake may be seized over any rolling 7 days.
Risk
Running from an announced seizure costs more than the seizure. Leaving immediately costs 70% of your stake; the seizure takes at most 30%, and in practice a fraction of that, because the protocol's own lot absorbs it first. The ordering is deliberate: the first delay of the grid is longer than the delay before a seizure can start.
Rules R-19.3.1, R-19.2.5
What FBR is not
It is not a governance token for version 1: nothing in the protocol can be changed by anyone, so there is nothing to vote on. The one vote that exists names an address that would be allowed to deploy a version 2, and it releases nothing from version 1. In that vote one address carries at most 10% of the private weight, however much it holds.
Risk
A third party could stake on behalf of many users and issue a liquid receipt against it. That receipt would escape the exit grid, since the underlying stake never leaves, and its holders would hold none of the boost, the shield or the multiplier individually, because those are computed per address. Nothing in the protocol prevents such a contract from existing.
It is not a source of yield for sfyUSD. It is not an asset whose price steers a risk parameter. It is not tail insurance: the dollar value of the staked layer is small against the debt it stands behind, and the specification calls it noise rather than cover. Season counters are counters: not a promise, not an asset, not a debt.
FBR can be worth nothing without anything breaking for a borrower or a depositor. That is the property the whole design is arranged around, and in the first year it is not a hypothetical: the emission is at its largest, the buy-back is at its smallest, and nothing in the contracts supports a price.
Rules R-19.14, R-15.4.1 (14)
Provide liquidity
Put a stock token and fyUSD into the vault of its branch, lock it, and be paid in staked FBR. What the vault does with them, what it costs you when the stock moves, and what the programme actually buys.
Corporate actions
Splits, dividends, mergers and delistings — what the protocol does by itself, what it deliberately does not do, and the one case that can cost you with no safeguard.