sBTC is a SIP-010 token on the Stacks blockchain that represents Bitcoin at a one-to-one ratio. Minting it moves real BTC into a Bitcoin wallet controlled by a rotating signer set, and returns a token that Stacks smart contracts can use. It is a peg, not a copy of Bitcoin, and the difference is where the risk sits.
sBTC at a Glance
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Metric
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Details
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Asset
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sBTC, a SIP-010 fungible token with 8 decimals
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Blockchain
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Stacks, which settles its blocks against Bitcoin
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Contract
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`SM3VDXK3WZZSA84XXFKAFAF15NNZX32CTSG82JFQ4.sbtc-token`
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Backing
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1:1 against BTC held in a signer-controlled Bitcoin wallet
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Supply, contract read Tuesday 25 August 2026
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2,441.31581778 sBTC
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Peg size, DefiLlama close Monday 24 August 2026
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$189,136,241 across 2,439.28670 BTC
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Live signer set, registry read Tuesday 25 August 2026
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11 public keys, signature threshold of 8
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Deposit and withdrawal
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Deposit inside roughly 3 Bitcoin blocks, withdrawal inside roughly 6
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Minimum mint
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0.001 BTC, or 100,000 sats, through the sBTC Bridge
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Mainnet deposits live
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Tuesday 17 December 2024
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Core risks
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Signer liveness, withdrawal rejection, contract upgrade authority
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Availability on Phemex
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sBTC is not listed on Phemex. BTC perpetual futures are
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What Is sBTC?
Every attempt to make Bitcoin programmable has to answer the same question. Where does the real BTC sit while a token stands in for it somewhere else?
sBTC answers that with a threshold-signed Bitcoin wallet. You send BTC to an address the signer set controls, the signers observe the deposit, and a Stacks contract mints you an equal amount of sBTC. Burn the sBTC later and the signers sweep the same amount of BTC back out to a Bitcoin address you nominate. DefiLlama classifies the whole arrangement as a bridge, which is the most useful one-word description of it.
The scale is smaller than the marketing suggests. Reading the token contract directly on Tuesday 25 August 2026 returns a total supply of 2,441.31581778 sBTC. DefiLlama's independent count of the Bitcoin behind it was 2,441.31615 BTC, a difference of 0.0003 BTC, or 0.000014%. Two separate measurements agreeing to five decimal places is the strongest evidence available that the peg is genuinely full.
Our companion piece on Stacks the Layer 1 covers the chain itself, the STX token and its supply structure. This one stays on the asset and the mechanism.
Why Does sBTC Exist?
Roughly $9.2 billion of Bitcoin sits inside Wrapped Bitcoin on Ethereum, against $196.9 million inside sBTC, both measured on DefiLlama on Tuesday 25 August 2026. That gap is the demand sBTC is chasing. Bitcoin holders want lending, decentralized exchange liquidity and the rest of what DeFi offers, and getting there historically meant handing BTC to a custodian and accepting an IOU. Stacks pitches sBTC as the version where no single custodian holds the keys, with the BTC behind a multi-party threshold signature rather than one company's cold storage.
One phrase causes most of the confusion in this corner of the market. Bitcoin staking, as Babylon uses the term, means locking BTC on the Bitcoin chain itself under a timelock script so it can secure a proof-of-stake network, with slashing as the penalty for misbehaviour. Stacks runs a separate product under a similar name where BTC also stays under the holder's own keys and where there is no slashing at all. sBTC is neither of those. Minting sBTC moves your Bitcoin into a wallet you do not control, and that single fact separates it from every model that keeps BTC on Bitcoin.
How Does sBTC Work?
The mechanism lives in four contract calls, and you can read all four in the registry contract's public interface without trusting anyone's description of it.
A deposit calls
complete-deposit, which takes the Bitcoin transaction ID, the output index, the amount, your Stacks address and the sweep transaction that moved your BTC into the peg wallet. Only the signer protocol can make that call. The documentation puts the round trip inside about three Bitcoin blocks, with sBTC typically arriving after one or two confirmations.A withdrawal is the interesting half. You call
create-withdrawal-request with an amount, a maximum fee and a Bitcoin address. The signers then call either complete-withdrawal-accept, which sweeps the BTC out and records which signers approved through a bitmap, or complete-withdrawal-reject, which does not. Six Bitcoin blocks is the stated window, roughly two hours, and the extra confirmations exist so the Stacks transaction finalises and the signers have time to verify the request.Two more functions matter and almost nobody mentions them.
rotate-keys replaces the signer list, the peg wallet address, the aggregate public key and the signature threshold in one call, and the deposited BTC moves to a new multisig each time. update-protocol-contract swaps out the protocol contracts themselves under a governance role. The rules governing your Bitcoin are changeable by design, and reading the registry contract on a Stacks explorer is the only way to see what they are at any given moment.sBTC vs Wrapped Bitcoin
Both assets do the same job. They differ in who has to fail before your Bitcoin does.
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Category
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sBTC
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Wrapped Bitcoin (WBTC)
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Home chain
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Stacks, anchored to Bitcoin
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Ethereum and several Layer 2 networks
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Who holds the BTC
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A threshold-signed peg wallet, 11 keys with a threshold of 8 as of Tuesday 25 August 2026
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A named custodian holding reserves on behalf of merchants
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Who can mint
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The signer protocol, after a confirmed Bitcoin deposit
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Approved merchants through a custodial workflow
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Failure mode
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Signer collusion, or signer downtime freezing the peg wallet
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Custodian insolvency, seizure or refusal to redeem
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Peg size, DefiLlama, Tuesday 25 August 2026
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$196.9 million
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$9.2 billion
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Redemption promise
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1:1, subject to the signers accepting your request
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1:1, subject to the custodian honouring it
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The fair summary is that sBTC replaces one trusted party with a small committee. That is a real improvement in the number of independent failures required, and it is a long way from Bitcoin's own security model. If you want the version where nothing leaves your keys at all, a hardware wallet holding native BTC remains the only answer.
What Are the Trust Assumptions?
SIP-028, the specification that governs the peg, states these plainly, which is more than most bridges manage.
The safety threshold is 30 percent
The specification says the system is safe if at least 30% of signer voting power is non-colluding, and that under that condition no theft of funds can occur. Read the inverse. If more than 70% of the signer set colludes, the Bitcoin in the peg wallet can be spent.
The liveness threshold is 70 percent
The system is live only if at least 70% of voting power is online and behaving. Fall below that and withdrawals stop processing. The specification is blunt about where that ends up. If more than 30% of signers go permanently offline, the BTC in the peg wallet becomes locked.
The signer set is smaller than advertised
SIP-028 was written around 15 independent entities, with 11 of 15 signatures needed to hit the 70% bar. Reading the registry contract on Tuesday 25 August 2026 returns a signer set of 11 public keys and a signature threshold of 8. The project's own signer page lists twenty organisations, including custodians such as BitGo, Copper and Hex Trust, staking operators such as Blockdaemon, Kiln and Chorus One, and a major centralized venue, under a footnote saying only a subset of them sign sBTC transactions. Eight cooperating keys is the number that actually governs your Bitcoin.
Withdrawal is a request, not a right
complete-withdrawal-reject exists in the contract. The project's own page describes sBTC rewards as redeemable 1:1 for BTC anytime, and the contract describes a request that eight of eleven keys have to approve. Both statements are true at once, which is exactly the sort of thing worth noticing before you deposit.Risks of Using sBTC
The peg has been shrinking
DefiLlama's Bitcoin count inside sBTC peaked at 5,015.80 BTC on Friday 6 June 2025 and read 2,439.29 BTC at the Monday 24 August 2026 close, a fall of 51.4%. Dollar TVL tells a flattering and misleading story over the same stretch, because it rose 21.8% between Monday 17 August and Monday 24 August 2026 while the Bitcoin in the peg fell 1.31%. That entire dollar gain was BTC's own price, which two feeds put at $79,734.91 and $79,691.69 on Tuesday 25 August 2026, a spread of 0.05%.
The yield most articles describe no longer exists
The sBTC Rewards Program that paid up to 5% APY to early holders sunset on Tuesday 4 November 2025. Its replacement, Dual Stacking, pays BTC-denominated rewards in sBTC, and the documentation is explicit that the large multiples come from also locking STX. Chasing the headline rate means taking STX price exposure on top of peg exposure, which is a different trade from holding Bitcoin.
Smart contract risk is additive
sBTC is only useful once it enters a lending market or a liquidity pool, and each of those is a separate contract with its own failure history. Bridge and DeFi exploits through 2026 have overwhelmingly hit the wrapper layer rather than the base chain.
Liquidity is thin
A peg holding under $200 million cannot absorb a large exit quickly. Anyone sizing a position should assume the exit is slower and more expensive than the entry, particularly during the sort of volatility that makes people want to exit.
Published figures disagree with each other
A project press release dated Monday 27 April 2026 reported sBTC closing the first quarter of 2026 at $437 million with a peak of $545 million inside the quarter. DefiLlama's series for the same asset reads $271,065,604 on Tuesday 31 March 2026, with a quarterly high of $437,138,240 on Thursday 15 January 2026. The gap between the two closing figures is 61.2%. Do not build a position on either number without checking which one your source used.
How to Verify an sBTC Position Safely
Every claim in this article was checked against the chain rather than a dashboard, and you can run the same checks in about ten minutes.
Start with the token contract. Call
get-total-supply on SM3VDXK3WZZSA84XXFKAFAF15NNZX32CTSG82JFQ4.sbtc-token through any Stacks node and divide by 10^8, which gives you the sBTC in existence with nothing standing between you and the number.Then read
get-current-signer-data on the sibling registry contract. It returns the aggregate public key, the signature threshold and the full list of signer keys in one response, so you can count the committee yourself instead of counting logos on a marketing page. Compare that supply against an independent Bitcoin-side count such as DefiLlama's, where agreement to several decimal places means the peg is full and a widening gap is the first thing that would break.Finally, date every figure and name its feed. The 61.2% disagreement over a single quarter's closing TVL is what happens when a press release and a tracker measure on different days and everyone downstream repeats one of them. The same discipline applies across Ethereum's Layer 2 networks, where headline totals and on-chain reality routinely diverge.
Is sBTC Worth Using?
The honest answer depends on what you want the Bitcoin for. If the goal is holding BTC, sBTC strictly adds risk and returns nothing, because the base asset already does the job and Bitcoin's own security model has no committee in it.
If the goal is putting Bitcoin to work in Stacks DeFi, sBTC is a defensible way to do it, on the same logic that makes stETH a reasonable representation of staked Ethereum. You are accepting eight-of-eleven signer cooperation, contract upgrade authority and a peg under $200 million in exchange for programmability.
What does not hold up is the framing that you keep custody. You do not. The BTC moves, and the peg is a small committee behaving well and staying online.
Final Thoughts
Two numbers decide how this ends, and neither is the dollar figure everyone quotes. The first is the Bitcoin count inside the peg, which has to stop falling before any recovery story means anything. The second is the length of the signer list in the registry contract, because a threshold set that keeps getting shorter needs fewer parties to cooperate against you. Both are readable from the chain in a couple of minutes, both update continuously, and a marketing page will report neither. Check them before you mint, and check them again before you size anything up.
Frequently Asked Questions
Is sBTC actually backed one-to-one by real Bitcoin?
As of Tuesday 25 August 2026 the token contract reported 2,441.31581778 sBTC against DefiLlama's independent count of 2,441.31615 BTC, a 0.000014% difference. The backing is genuinely full, and the open question is not the reserve, it is who has to cooperate for you to get it back.
Can the sBTC signers freeze or take my Bitcoin?
Taking it would require more than 70% of signer voting power to collude, which SIP-028 states as its safety assumption. Freezing is the easier failure. If more than 30% of signers go permanently offline the specification says the peg wallet becomes locked, and the contract also contains an explicit withdrawal reject function.
Does holding sBTC pay yield?
Holding the token on its own no longer pays anything. The rewards program that paid up to 5% ended on Tuesday 4 November 2025, and its replacement pays meaningfully only when you also lock STX, which introduces exposure to a second asset. Anyone quoting a flat 5% for simply holding sBTC is working from stale material.
How long does converting sBTC back to BTC take?
The documented window is six Bitcoin blocks, so roughly two hours in normal conditions, against about three blocks for a deposit. The asymmetry is deliberate, since the extra confirmations give the signers time to verify the request before Bitcoin leaves the peg wallet.
This article is for informational purposes only and does not constitute financial or investment advice. Cryptocurrency trading involves substantial risk. Always conduct your own research before making trading decisions.
