Stacks approves SIP-045 Bitcoin staking upgrade, setting up hard fork around July 29

More than 99% of votes backed the proposal, which adds bitcoin-denominated yield through timelocked BTC bonds and restores the STX coinbase to 1,000 per Bitcoin block.

STX

Summary

Stacks approved SIP-045, the Bitcoin Staking upgrade, with more than 99% of votes cast in favor, paving the way for a hard fork targeted for around July 29 at roughly Bitcoin block 907,740. The proposal, formally called "PoX-5: Bitcoin Staking and Emission Schedule Alignment," allows participants to lock BTC in a timelocked contract on Bitcoin's base layer under their own keys, pair it with locked STX and earn yield paid in bitcoin. A companion proposal, SIP-044, which adds Clarity 6 and new staking post-conditions, also passed. The mechanism uses a timelocked Bitcoin UTXO funded with OP_CHECKLOCKTIMEVERIFY and verified by a Stacks contract using an SPV proof, avoiding a custodian or trusted bridge. Participants must pair the BTC bond with an STX lock worth at least 5% of the bond and commit for roughly six months. Yield is sourced from the BTC miners already bid through Proof of Transfer, with paired bonds targeting about 3% APY in BTC, STX-only stackers receiving 85% of excess rewards and 15% directed to a reserve that helps cover shortfalls. There is no slashing, and principal is returned when the timelock expires. The bootstrap phase will cap capacity at 3,000 BTC, managed by the Stacks Endowment with whitelisted partners and about 10% 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 by restoring the STX coinbase to 1,000 STX per Bitcoin block from 500. Bithumb separately said it will suspend STX deposits and withdrawals from 12:00 a.m. UTC on July 29 to support the network upgrade. Despite the vote, STX traded at $0.144, down 13% in 24 hours, while Bitcoin fell 1.9%, according to CoinGecko.

Terms & Concepts
  • SPV proof: A method for verifying a Bitcoin transaction or lock using block data without relying on a full custodian or bridge.
  • OP_CHECKLOCKTIMEVERIFY: A Bitcoin scripting feature that locks coins until a specified time or block height.
  • Proof of Transfer: Stacks' mechanism in which miners commit bitcoin to participate in block production and network rewards.