Function (FBTC)

About

Function is a protocol that issues FBTC, an omnichain Bitcoin yield asset fully backed 1:1 by native BTC reserves. It transforms passive Bitcoin into a liquid, composable asset that can be deployed across DeFi protocols for lending, staking, vault strategies, and restaking, while maintaining full on-chain reserve transparency through publicly verifiable custodial addresses.

Where Does Yield Come From?

FBTC comes in two versions. Standard FBTC (FBTC0) is a 1:1 Bitcoin-backed token that does not earn yield on its own, but you can move it into different DeFi apps. Locked FBTC (FBTC1) is a token built specifically for earning yield.

Here is how the yield process works:

People who hold FBTC0 deposit it into vaults run by partner projects.
The vault converts FBTC0 into FBTC1 and moves the supporting Bitcoin into special yield-earning addresses that the partner controls.
The partner then puts that Bitcoin (in the form of FBTC1) into approved yield strategies. These can include:
- Lending protocols (like Aave, Avalon, Takara) — platforms that lend out deposits for interest.
- Yield aggregators (like Cian, Sentora, Kamino) — automated vaults that constantly move money between lending and borrowing to maximize returns.
- Restaking (like Babylon, EigenLayer, SatLayer, Pell Network, Karak) — reusing staked assets to secure other networks for extra rewards.
- Liquid staking (like Bedrock, Lombard, PumpBTC, Solv) — wrapping staked Bitcoin into a tradable token.
- DEX liquidity pools — providing funds for crypto exchanges to earn trading fees.
The yield earned flows back to FBTC1 holders through the partner vaults.

Who can mint or burn FBTC? Only verified merchants (who have passed KYC/AML checks) can create or destroy FBTC. They pay a bridge fee and on-chain gas fees each time. The protocol does not set a fixed fee percentage — each merchant and each bridge has its own fee arrangement.

Extra rewards: There is also a separate Points program (tracked at fxn.xyz/points) that may add bonus incentives on top of the regular DeFi yields.

Persons

Thomas Chen
CEO
LinkedIn
Zuki Hong
Growth Lead

Audits

Audit / Date	Findings	Verdict
BlockSec20-06-2024	Critical0 High0 Medium0 Low3 Info1	BlockSec's audit identified three low-severity software issues, all of which were fixed by the project team in the subsequent commit, with no critical, high, or medium findings outstanding. The residual centralization risks noted are architectural design considerations inherent to the bridge model rather than exploitable vulnerabilities.
MixBytes09-05-2024 - 25-06-2024	Critical0 High0 Medium3 Low7 Info0	The audit found no critical or high-severity vulnerabilities, and the three medium-severity issues (centralization, chain whitelisting, fee monotonicity) were either fixed or acknowledged, with the seven low-severity items largely resolved. Residual centralization risks remain by design but are planned to be mitigated via a timelock or DAO transition.
Secure320-06-2024	Critical0 High0 Medium5 Low8 Info8	The audit revealed no critical or high-severity vulnerabilities in the FBTC codebase; all five medium-severity issues were either remediated, acknowledged with compensating off-chain controls, or declined by design. Residual safety considerations center on centralized privileged roles, which the team manages via a DAO Safe Multisig and plans to transition to timelock or DAO governance.
BlockSec17-06-2024	Critical0 High0 Medium0 Low2 Info1	The audit found no critical, high, or medium severity issues; the two low-risk findings were acknowledged with project-side mitigations described, and the centralization note highlights a privileged emergencyBurn capability that is an intentional design property. Overall, the contract exhibits no unaddressed high-severity vulnerabilities per this audit scope.
Secure3—	Critical0 High0 Medium0 Low2 Info2	All four findings (2 Low, 2 Informational) were remediated by the client, and no critical, high, or medium severity issues were identified, indicating that the LockedFBTC contract had a solid security posture at audit conclusion.

Backers

Function raised a $10M seed round on August 15, 2025 (per Crunchbase data listed on its LinkedIn profile). Investors in the round include Galaxy Digital and at least one other investor. The protocol's official website and whitepaper list Antalpha (Antalpha Prime) and Mantle as initial core contributors and backers. The "About" page states the protocol is "Backed by Antalpha, Galaxy, Mantle and others on its security council." The whitepaper further notes that Cobo is an early partner and serves on the Security Council alongside Mantle and Antalpha Prime, overseeing BTC custodian MPC multi-signature and bridge TSS node operations. No additional funding rounds or specific amounts beyond the $10M seed round were publicly disclosed on the official website or whitepaper.

Legal

Legal form

Private limited company (Limited)

Registration jurisdiction

Hong Kong

Status and notes

The operating entity is FireSpire Limited, as disclosed in the Terms of Service and Risk Disclosure Statement. The Terms are governed by the laws of Hong Kong, with disputes resolved by arbitration at the Hong Kong International Arbitration Centre (HKIAC). A link to the Terms of Service, Privacy Policy, and Risk Disclosure Statement is provided in the website footer. Legal contact: [email protected]. No official company registry number or incorporation date is disclosed on the website or whitepaper.