Stacks sBTC

Rejected venues wait the longest for re-review; a rejection has to earn another look before the scheduled date.

REJECTED ON UNCONFIRMED WITHDRAWAL TIMING, DESPITE A SIGNER COMMITTEE COMPARABLE TO AN ALREADY-APPROVED PEER. sBTC uses a genuinely different design from custodial wrappers: 14 to 15 elected signers, including named entities such as Figment, Blockdaemon, and Kiln, approve mints at a roughly 70% threshold rather than a small custodial multisig — a committee comparable in size to Lombard BTC.b’s approved 14-member, 10-of-14 Security Consortium. But Stacks’ own documentation does not specify deposit or withdrawal timing for either direction, and this review could not confirm the peg-out mechanics anywhere. A comparably sized committee is not sufficient on its own; without confirmed exit terms this registry cannot certify what a stressed redemption would actually look like.

Kill criteria: the events that revoke this verdict
• Withdrawal or peg-out timing and mechanics are independently confirmed and demonstrated at proposed size
• Current signer count and threshold are confirmed precisely, resolving the discrepancy across sources
• Phase 3’s permissionless, Proof-of-Transfer-integrated signer model is implemented and independently verified
• Twelve consecutive months with no depeg or signer-related incident following the above disclosures

The research file

Mechanism

A depositor sends BTC to a multisignature address controlled by a group of signers, formatted for sBTC; the Emily API service tracks the incoming deposit and alerts signers, who mint an equivalent amount of sBTC to the depositor’s Stacks address once confirmed. Withdrawal, or ”peg-out,” reverses this process, but Stacks’ own documentation does not specify timing for either deposits or withdrawals — a real, unresolved disclosure gap.

Control and governance

The system is currently in ”Phase 1”: 14 to 15 elected signers, sources give both figures, reviewed and voted on by the Stacks community — a curated, not permissionless, process despite marketing language describing this as a decentralized alternative to custodial wrapped BTC. The reported threshold is 70%, described elsewhere as either 10-of-14 or 11-of-15 depending on the source. Selection criteria include blockchain-infrastructure experience, uptime commitments above 99%, and geographic diversity. A future ”Phase 3” is planned to make the signer set open, permissionless, and rotating, integrated with Stacks’ Proof-of-Transfer consensus, but that is a roadmap item, not the live state.

Incident record

No exploit of sBTC’s own signer, mint, or redeem mechanism was identified. A June 2025 exploit of ALEX Protocol, a DeFi application built on Stacks but not sBTC itself, drained about 21.85 sBTC among other assets via a failed-transaction-verification bug in ALEX’s own contracts. Some price feeds showed sBTC trading materially off-peg afterward; a Stacks representative disputed this, pointing to a different oracle feed showing sBTC on-peg throughout — an unresolved discrepancy between data sources, not a confirmed sBTC-level depeg, and an application-level failure adjacent to sBTC rather than a failure of sBTC’s own bridge or custody.

Exit

Peg-out from sBTC to BTC exists mechanically, but this review could not confirm typical completion timing from Stacks’ own documentation — a material gap for a product whose core marketing claim is a more accessible, on-chain redemption path than custodial wrappers offer.

Comparison

Committee size, 14 to 15 signers at roughly a 70% threshold, is comparable to Lombard BTC.b’s approved 14-member, 10-of-14 Security Consortium, and larger than WBTC’s rejected 2-of-3 or Function FBTC’s rejected, unconfirmed three-party threshold. But two gaps keep this below Lombard’s bar: the signer set is currently curated and elected rather than open, though that alone is not disqualifying since Lombard’s named institutions are similarly curated, and, more decisively, withdrawal timing is unconfirmed here, unlike Lombard’s disclosed nine-to-ten-day redemption window or Kraken’s disclosed KYC-gated process.

Sources

The claims above trace to these. Where a number could not be independently verified, the thesis says so.

• Hiro — who are the sBTC signers: breaking down SIP-028 · primary · accessed 2026-08-18
  Supports: signer count, election process, threshold, Phase 3 roadmap
• Stacks — SIP-028 update: alternate sBTC signer election upcoming · primary · accessed 2026-08-18
  Supports: signer election process
• Stacks Docs — bridging Bitcoin · primary · accessed 2026-08-18
  Supports: deposit mechanism, Emily API, no withdrawal timing specified
• Cryptonews — Bitcoin DeFi project ALEX exploited again, aBTC and sBTC depeg · secondary · accessed 2026-08-18
  Supports: June 2025 incident, disputed depeg readings
• Protos — Bitcoin DeFi project ALEX exploited again · secondary · accessed 2026-08-18
  Supports: same incident, oracle counter-claim

Inherited controls

The verdict above grades the protocol layer. Every position also inherits the asset it holds and the chain it settles on. The least safe layer sets the position’s grade, and the position table names which one that is.