STX Block Reward
The fixed STX emission per Bitcoin block paid to the winning miner. Currently 500 STX, proposed to be set indefinitely at 1,000 STX under Bitcoin Staking to remove previously scheduled halvings.
Stacks Protocol Terms
Staking vs. Stacking
Stacking refers to the prior PoX-4 model where locked STX alone earned BTC rewards. Staking is the term under Bitcoin Staking, reflecting the expanded dual-asset (BTC + STX) commitment model.
Stacks Protocol Terms
Stacks Signer
A node operator responsible for validating Stacks blocks under Nakamoto consensus. Signing weight is a function of locked STX, and stakers may run their own signer or delegate to a third-party operator.
Stacks Protocol Terms
sBTC
A 1:1 bitcoin-backed programmable asset on Stacks. Can be used in protocol bonds to satisfy the Bitcoin commitment in place of a native L1 timelock.
Stacks Protocol Terms
Proof of Transfer (PoX)
Stacks' consensus mechanism, in which miners transfer BTC to compete for STX block rewards and the transferred BTC is distributed to eligible participants. Live since January 2021 and the foundation Bitcoin Staking extends.
Stacks Protocol Terms
Nakamoto Consensus / SIP-021
The Stacks consensus upgrade that introduced fast blocks and a Stacks signer set responsible for block validation. It is the consensus layer Bitcoin Staking builds on but does not modify.
Stacks Protocol Terms
Miner Bid / BTC Bid
The BTC a Stacks miner commits in a given block round to compete for the right to produce the next Stacks block and earn the STX block reward and transaction fees. The sum of all miner bids is the source of yield for Bitcoin Staking.
Stacks Protocol Terms
Yield-Bearing Asset
BTC in its role as the asset that earns yield within a protocol bond. Only the BTC portion of a paired position accrues yield.
Bitcoin Staking Components
Waterfall Structure (Tranches 1 2 and 3)
The priority order in which the BTC reward pool is distributed each cycle. Tranche 1 pays target yield to active protocol bonds. Tranche 2 routes a share of the surplus pro rata to STX only stakers. Tranche 3 distributes the remaining excess to the Reserve Fund.
Bitcoin Staking Components
Target Yield
The annualized BTC rate the protocol expects to pay paired positions under normal conditions for a given bonding period. "Annualized" here means over a 52,560-block Bitcoin year (50 weekly cycles of 1,050 blocks), not a 365 day calendar year. Bonding periods can have different target yields. For a new bonding period, the protocol defaults to the BTC weighted blended yield of the active bond book. Realized payout over a bonding period may vary slightly from the headline target.
Bitcoin Staking Components
Reserve Fund
A safety reserve, held in BTC and stablecoins, that the protocol uses to supplement BTC yield distributions when miner revenue falls short. Funded by setting aside a portion of the leftover BTC after primary yield obligations are paid.
Bitcoin Staking Components
Protocol Bond
A dual-asset commitment in which a participant pairs a BTC timelock on Bitcoin L1 (or sBTC on Stacks) with an STX lock on Stacks for one bonding period, in exchange for protocol yield denominated in BTC.
Bitcoin Staking Components
Early Exit
An optional pre-approved spend path that lets a participant unlock their L1 BTC before the timelock expires. Exercising it forfeits all remaining yield, and the paired STX stays locked for the full term.
Protocol Time Periods and Phases
Coverage Ratio
A system health metric defined as the per-cycle BTC reward pool divided by paired BTC obligations. The per-cycle obligation per bond is (annual APY / 50), reflecting the Bitcoin-year basis on which APY is quoted.
Bitcoin Staking Components
Clearing Yield
The highest accepted bid in a bonding period's auction. Under uniform price clearing, all winning bidders are paid this rate regardless of their individual bid. The clearing yield is quoted as an annualized rate on a 52,560-block Bitcoin year; per-bond payout = (clearing yield / 50) × 24.
Bitcoin Staking Components
Capacity Asset (STX)
STX in its role as the token that determines a participant's share of the BTC reward pool. STX provides gas, consensus, and governance utility but earns no yield when paired in a bond.
Bitcoin Staking Components
Signer Cycle
A 2,100 block (approximately 14 day) PoX unit that governs Stacks signer set updates, STX only enrollment, and block validation under Nakamoto consensus.
Protocol Time Periods and Phases
Re-lock Phase
The final 1,400 blocks (approximately 10 days) of a bonding period during which the L1 BTC timelock has expired but STX remains locked, giving participants time to construct a new L1 lock for the next bonding period.
Protocol Time Periods and Phases
Enrollment Period (PoX-5)
The bootstrap phase equivalent of the Auction Period, opening once a month for approximately one week, during which the Stacks Endowment sets capacity and allocates it to whitelisted partners.
Protocol Time Periods and Phases
Distributions (Payouts)
Weekly BTC reward distributions to eligible participants, paid every 1,050 Bitcoin blocks (one Bitcoin week, approximately 7 days). There are 24 distributions per bonding period and 50 weeks per Bitcoin year (52,560 blocks), so two consecutive bonds produce 48 distributions, approximately 96% of one full Bitcoin year's APY. The remaining ~2 weeks of a Bitcoin year sit outside a back to back bonding schedule.
Protocol Time Periods and Phases
Confirmation Phase (L1 Lock Up)
The window between auction clearing and Day 0 in which successful bidders must complete their L1 BTC timelock. Failure to lock in time forfeits the allocation.
Protocol Time Periods and Phases
Bonding Period
The full 25,200 block (approximately six month) term during which paired BTC and STX are locked and earn yield. Six bonding periods run concurrently in staggered, monthly offset sequences.
Protocol Time Periods and Phases
Bidding Phase
The portion of the auction window during which participants submit sealed bids specifying their desired BTC amount and minimum acceptable yield, before a bonding period opens.
Protocol Time Periods and Phases
Auction Period (PoX-6)
A monthly window (4,200 Bitcoin blocks) in which a new bonding period is opened and capacity is allocated through a permissionless sealed-bid auction. Replaces the Enrollment Period used during the PoX-5 bootstrap phase.
Protocol Time Periods and Phases
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