Stacks activates its PoX-5 hard fork at Bitcoin block 960,230, adding the consensus infrastructure for Bitcoin staking. The upgrade introduces Bitcoin Bonds, which pair BTC locked on Bitcoin with STX on Stacks to earn BTC denominated yield. Existing STX stakers must restake after activation to keep receiving BTC rewards.
Stacks is set to activate its PoX-5 hard fork this week, introducing the consensus infrastructure needed to support Bitcoin staking on the network. Activation is scheduled for Bitcoin block 960,230, currently expected around 2 a.m. Eastern Time on Thursday, July 30, and the precise timing may change depending on how quickly Bitcoin blocks are produced.
Bitcoin Bonds keep BTC on Bitcoin layer one
PoX-5 upgrades Proof-of-Transfer, the Stacks consensus mechanism under which miners commit BTC to compete for the right to produce Stacks blocks and receive STX rewards. On top of that, the upgrade introduces Bitcoin Bonds, which let users lock BTC on the Bitcoin network and pair it with STX on Stacks to earn BTC denominated yield while retaining control of their Bitcoin keys.
Stacks describes the structure as a protocol bond: Bitcoin remains locked on Bitcoin layer one, while the corresponding STX position is held through a Stacks smart contract, and yield is funded by the BTC that miners commit through Proof of Transfer. The bonds activate at the consensus level with the hard fork, although participation will open gradually, with initial capacity reserved for approved participants during a bootstrap period. Stacks expects the first institutional Genesis Bond in late August, followed by community participation through selected pools using sBTC.
Existing stakers must restake before block 962,050
The hard fork does not create a new token and will not affect STX balances, wallet addresses, or private keys, so holders who are not staking need to take no action. Existing stakers do: all STX committed through the previous contract unlocks during the upgrade as staking moves to the new PoX-5 contract.
Users must restake before Bitcoin block 962,050 to receive rewards during the first cycle after the hard fork. Solo stakers can restake once the upgrade becomes active, while pool participants must wait for their provider to update its infrastructure and reopen staking. PoX-5 also removes the previous cooldown cycle, allowing stakers to change their reward address without missing a full cycle.
STX-only stakers take 85% of the remaining miner rewards
Bitcoin Bonds receive their target yield first. Of the remaining BTC committed by miners, 85% goes to STX only stakers, while 15% enters a reserve fund intended to support future payouts. Stacks said STX only participants are expected to receive most of the miner rewards during the early cycles because Bitcoin Bond capacity will initially remain limited.
Around activation, exchanges supporting STX may temporarily suspend deposits and withdrawals while upgrading their infrastructure, though trading is expected to continue. Node operators must upgrade to stacks core version 4.0.1 before block 960,230 to remain connected once the new consensus rules take effect. The codebase has been audited by Trail of Bits and Clarity Alliance, with additional review from Asymmetric Research.
Stacks notes that target yields are not guaranteed and remain dependent on miner participation and network conditions.
Source: Crypto Briefing
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