Fractal Bitcoin completes its first halving without a hiccup
Fractal Bitcoin has cleared one of the biggest tests in its short life as a Bitcoin sidechain. The network completed its first scheduled halving at block 2,100,000, cutting the block reward on the Fractal side from 25 FB down to 6.25 FB after the FIP-102 consensus upgrade took effect. According to a September 8 post from the Fractal Bitcoin team on X, the halving went through cleanly, with nodes and indexing services reported as operating normally during the first ten minutes after activation. The team said it would continue monitoring the network and invited users to report any service-related problems.
Halvings are always stressful moments for a proof-of-work network. Miners suddenly earn half of what they did a block earlier, and any consensus bug in the activation logic can split the chain. Fractal avoided both problems, at least in the opening stretch, and the smooth rollout gives the project something to build on as it pushes toward its more unusual goal: distributing FB tokens directly on Bitcoin mainnet.
What FIP-102 actually changes
FIP-102 is a consensus upgrade that changes how future FB emissions are distributed, and it does two things at once. First, it executed the network’s first halving, cutting the block reward from 25 FB to 12.5 FB. Then, in the same activation, it brought the second halving forward, cutting the reward again to 6.25 FB per Fractal block. The remaining 6.25 FB per block equivalent has not been destroyed. Instead, it has been set aside as an emission budget for future distribution on Bitcoin mainnet.
Importantly, the proposal does not increase FB’s total supply or create a second pool of tokens for the Bitcoin-side distribution. The budget carved out by FIP-102 will not be distributed at its full rate immediately. The project plans a progressive rollout, spreading the Bitcoin mainnet distribution over roughly three months once the framework is ready.
Fractal’s existing mining structure stays intact. Blocks on the Fractal side continue to be assigned across three mechanisms: Merged Mining, Permissionless Mining, and Index Mining. The three share rewards at a 1:1:1 ratio, meaning one block in every three-block cycle goes to each category. Before the halving, with 25 FB emitted per block, each mechanism received an average of roughly 8.33 FB per block across the cycle. After FIP-102, each eligible Fractal block carries a 6.25 FB reward, which averages out to approximately 2.0833 FB per block for each of the three mining tracks.
FB distribution is moving to Bitcoin mainnet
The Bitcoin allocation under FIP-102 is the part that sets Fractal apart from typical halving stories. The design lets users obtain FB through eligible interactions directly on Bitcoin rather than limiting new distribution to activity on the Fractal chain itself. A 1:1 conversion mechanism between FB on Fractal and FB on Bitcoin mainnet is planned under the same framework. Converting a token between the two environments will not mint an extra unit of FB, which keeps both representations inside one unified supply.
The specifics are being left to a follow-up proposal. FIP-103 will define the remaining technical details, including which interactions qualify, how the distribution mechanism works, rollout requirements, and the process for converting FB between Fractal and Bitcoin. The timeline laid out by the team calls for research and implementation work to continue for three to six months, with testing scheduled to begin in the fourth quarter of 2026 and a full rollout targeted for the first quarter of 2027.
The merged mining connection
The mainnet distribution plan builds on Fractal’s existing relationship with Bitcoin miners. In April 2025, the project added Foundry to its merged-mining network, giving the protocol access to computing power equivalent to 93 percent of Bitcoin’s hashrate at the time. Fractal and Bitcoin both use the SHA-256 hashing algorithm, which allows miners to secure both networks through merged mining without dedicating separate computing power to each chain. That shared security model is what makes the idea of distributing FB through Bitcoin-mainnet activity practical rather than theoretical.
Halvings in context
The reward reduction follows the same basic supply mechanism used by Bitcoin, where scheduled halvings periodically reduce new issuance. Bitcoin itself currently pays miners 3.125 BTC per block following its April 2024 halving, with the next reward reduction expected around 2028. The block subsidy falls by 50 percent every 210,000 blocks, steadily slowing the rate at which new coins enter circulation. Fractal copied that cadence and compressed it: instead of waiting years between halvings, its schedule brings reductions much faster, which is why the network has already staged its first two reductions in a single activation.
For miners on the Fractal side, the immediate effect is a 75 percent cut in per-block issuance compared with the pre-halving rate of 25 FB. Whether that pressure is offset by fee activity and the promise of future mainnet distribution incentives is the question the market will answer over the coming months. For now, the network held together through its most delicate transition yet, and the road to a unified FB supply across Fractal and Bitcoin now runs through FIP-103.
Market snapshot at time of writing: Bitcoin trades near 78,400 USD, Ethereum around 2,474 USD, and Solana near 103 USD.
Disclaimer: This article is for informational purposes only and does not constitute financial advice.
Reward went 25 to 6.25 in one activation because FIP-102 pulled the second halving forward. Miners just took two halvings at once, that is brutal without price support.
this is what worries me too. indexing running fine is nice but hashrate bleeding out as miners shut down is the metric to watch the next two weeks.
watching hashrate on fractal specifically since merged mining with mainnet masks some of it. two halvings at once leaves zero margin for marginal miners
merged mining means marginal cost is the mainnet rig you already run. hashrate bleeding is less scary when your miners never left home
two halvings in one activation is exactly why im watching hashrate not price this week. if FB holds even half its security budget at 6.25 reward ill be impressed
Distributing FB directly on Bitcoin mainnet is still the most underrated part of this project. Though a first halving passing without a chain split is table stakes.
table stakes yes, but plenty of sidechains fumbled exactly this. ten clean minutes post-activation is more than some bigger names managed.
FB distribution straight on bitcoin mainnet is the part nobody copies. if the token lands there with real liquidity the sidechain thesis finally has a receipt
mainnet distribution also means no new bridge to trust for the token leg. half of sidechain deaths are bridging, removing it day one matters
^ exactly, bridges killed more sidechains than any halving ever did. token leg settling on mainnet removes the classic death vector
^ bridge risk gone still leaves fee markets untested tho, 6.25 FB blocks need actual usage not halving hype
^ usage is the whole ballgame now. reward cut 75 percent overnight, either inscription volume comes back or 6.25 FB blocks run on fumes
sidechain surviving its first halving with indexing services normal is quietly a big deal. one bug in the activation logic and the chain splits
agree, though now the real test is miner economics at 6.25 FB per block
6.25 FB per block only works if FB price roughly quadruples or fees pick up the slack. otherwise the security budget question gets loud fast
or fees. fractal inscription volume was carrying real fee weight before the halving, if that picks back up the security budget question answers itself
quadruple or fees pick up the slack, and inscription fees were carrying real weight before the halving. the budget question is real but not exactly new
or hashrate just consolidates into merged miners who treat FB as found money. the security budget only screams if fees and price both sit still
merged miners treating FB as found money is basically free optionality though. worst case they ignore it, best case fees print
quadruple feels like a stretch but inscription fees were carrying real weight before the cut per the onchain numbers. reality probably lands between your two cases
first halving clean at block 2,100,000 is nice but the pulled forward second halving is the real story. that reward curve is steep
clean activation at 2,100,000 is whatever, the FIP-102 curve with the second halving pulled forward is unhinged design. one fee market test stacked on another
6.25 FB per block and the distribution happens on bitcoin mainnet itself. no bridge risk day one is quietly the biggest de-risk in this whole halving story
6.25 FB reward with the second halving already pulled forward. whoever designed that curve wanted to stress test fee markets in real time
right, whoever wrote that reward curve skipped the gradual part entirely. fee markets usually get years to mature, fractal gets months
stress test is generous wording. pulling the second halving forward gives the fee market barely any runway before the budget question doubles again
reward cut from 25 to 6.25 FB at block 2,100,000 and no chain split, ten clean minutes post activation is honestly more than most sidechains manage