The Stacks community approved SIP-045, the proposal behind its Bitcoin staking upgrade, with more than 99% of votes cast in favor, according to Stacks co-creator Muneeb Ali. The result sets up a hard fork targeted for around July 29, near Bitcoin block 907,740.
The proposal is formally titled “PoX-5: Bitcoin Staking and Emission Schedule Alignment.” It allows participants to lock BTC in a timelocked contract on Bitcoin’s base layer while keeping custody under their own keys, then pair that position with locked STX to earn yield paid in bitcoin.
A companion proposal, SIP-044, passed alongside it. SIP-044 adds Clarity 6 and new staking post-conditions. Voting opened on July 6, and hard-fork votes require at least 80% approval from stacked STX.
When the Bitcoin Staking whitepaper was published in May, Ali said: “Bitcoin is the world's most trusted asset precisely because of its design and safety principles on the L1. Holders can now earn yield denominated in BTC, trustlessly, while their Bitcoin stays exactly where it belongs.”
How the staking design works
Under the mechanism, stakers fund a timelocked UTXO on Bitcoin using OP_CHECKLOCKTIMEVERIFY, pair it with an STX lock equal to at least 5% of the bond, and commit for roughly six months.
The Stacks contract verifies the Bitcoin-side lock through an SPV proof, so the design does not require a custodian or a trusted bridge. Yield comes from the BTC that miners already bid through Proof of Transfer. Paired bonds are designed to target about 3% APY in BTC. STX-only stackers receive 85% of the excess, while 15% is directed to a reserve intended to buffer shortfalls.
There is no slashing in the model. Principal returns in full when the timelock expires.
Bootstrap phase and launch timeline
The bootstrap phase caps capacity at 3,000 BTC. That phase will be managed by the Stacks Endowment together with whitelisted partners, with about 10% of capacity open to pools. A public testnet went live this week, and a “Genesis Bond” is targeted for late August.
SIP-045 also reverses April’s emissions cut. It restores the STX coinbase to 1,000 STX per Bitcoin block from 500, adding a meaningful supply increase alongside the staking mechanism.
Rewards history and market reaction
The Defiant said Stacks has distributed more than 4,200 BTC in stacking rewards since Proof of Transfer went live in 2021, or roughly $500 million.
According to DefiLlama data cited in the report, Stacks’ bridged asset sBTC currently holds about $186 million, down from a first-quarter peak of $545 million as BTC’s price fell.
The vote result did not lift the token. CoinGecko data cited by The Defiant showed STX trading at $0.144, down 13% over the past 24 hours, sharply lagging Bitcoin’s 1.9% decline.