Stacks launches PoX-5 testnet with 3,000 BTC staking cap

Stacks opened public testing for PoX-5, a protocol upgrade that lets Bitcoin holders stake BTC directly through self-custodial timelocks, with a mainnet hard fork targeted around July 29 and an initial 3,000 BTC capacity cap.

"PoX-5 introduces the ability to stake actual Bitcoin alongside STX, with the BTC remaining on Bitcoin's own blockchain secured by a timelock rather than a custodian," the Stacks ecosystem team said in the testnet announcement. The upgrade follows two governance proposals, SIP-044 (Clarity 6) and SIP-045 (Bitcoin Staking), which cleared community voting with approval exceeding 99.99%.

The bootstrap phase caps staked Bitcoin at 3,000 BTC, with a projected yield of approximately 3% APY paid in BTC and a minimum STX pairing ratio of 5%. The existing Proof of Transfer mechanism has maintained over 99.9% uptime since January 2021, distributing more than 4,200 BTC in rewards. Mainnet activation depends on Bitcoin reaching block height approximately 907,740.

The 5% STX pairing requirement creates a structural demand floor for the token: if the 3,000 BTC cap is filled, STX equivalent to at least 5% of that value must be locked alongside it. Timelocks eliminate counterparty risk but introduce liquidity constraints — stakers cannot exit positions during sharp BTC price moves. The Stacks roadmap targets PoX-6, a permissionless auction model, after PoX-5 stabilizes, with the Genesis Bond — described as the first Bitcoin Protocol Bond — expected in late August 2026.

This article is for informational purposes only and does not constitute investment advice.