Ethereum Fusaka Upgrade AI Report

Ethereum’s Fusaka upgrade activated successfully at slot 13,164,544 (epoch 411392) on December 3, 2025, at 21:49:11 UTC, marking the network’s second major hard fork of the year following May’s Pectra upgrade. Fusaka advances the “Surge” phase of Ethereum’s long-term roadmap, strengthening rollup-centric scaling and data availability. The name combines “Fulu” (execution-layer codename, after a star) and “Osaka” (consensus-layer codename referencing Devcon 2025’s host city). The upgrade includes around a dozen Ethereum Improvement Proposals (EIPs) focused on Layer-1 performance, blob throughput, and validator efficiency, without requiring any user action from ETH holders. Layer-2 networks—now processing the majority of Ethereum ecosystem transactions—are the immediate beneficiaries, with blob utilization rising after activation and Blob Parameter Only (BPO) forks opening the door to multi-phase capacity increases over time. Fusaka followed a smooth rollout across Holesky (Oct 1), Sepolia (Oct 14), and an additional testnet in late October, with early mainnet monitoring indicating stable finality and no critical incidents. This shift toward semiannual upgrade cadence positions Ethereum competitively against monolithic chains, maintaining a strong uptime record while enabling sustainable scaling without compromising decentralization.

At the technical core of Fusaka is EIP-7594 (PeerDAS: Peer Data Availability Sampling), a probabilistic protocol allowing validators to verify availability by sampling a small fraction of blob data per block instead of downloading entire blobs. Using cryptographic commitments and network-level sampling, validators can reconstruct availability guarantees efficiently, addressing the post-Dencun blob workload that burdened node bandwidth and storage with rapidly rising L2 data postings. PeerDAS supports future blob expansions beyond the current 6-blob target (max 9)—with developer projections estimating multi-fold capacity gains once the two-step BPO increases roll out: the first raising blob limits to 10/15 in December, followed by 14/21 in early January 2026. These changes are expected to lower L2 data costs substantially and support significant ecosystem-level throughput growth.

Additional Fusaka EIPs include EIP-7935 (raising the default block gas limit from 45 million to around 60 million for steadier throughput), EIP-7951 (introducing a native secp256r1 precompile, enabling P-256 cryptography for passkey-style wallet flows), and a set of Pectra-aligned validator improvements that streamline partial exits and consolidations. Other optimizations—such as proposer lookahead, blob fee refinements, and continued progress on history expiry—improve user experience and reduce node storage loads. Meanwhile, major roadmap items like Verkle trees, EOF, and potential block-time reductions remain scheduled for later upgrades beyond 2025, rather than for Fusaka itself.

Early post-upgrade metrics show healthy chain behavior. Client teams noted a brief increase in orphaned blocks from a small subset of non-updated nodes, but this resolved quickly following routine client patches. Layer-2 networks such as Arbitrum, Base, and Optimism reported modest short-term fee reductions attributed to the more efficient blob market introduced by Fusaka, though longer-term benefits depend on the phased BPO capacity increases expected in December and January.

Market reactions to the upgrade leaned cautiously optimistic. ETH held comfortably above $3,000, trading in the $3,030–$3,100 range after rebounding from late-October and early-November lows around $2,900. The broader crypto market added roughly $180 billion in capitalization to reach about $3.2 trillion, with scaling-focused assets outperforming amid renewed attention to rollup economics. Spot ETH ETFs recorded their first positive weekly flows in several months, taking in hundreds of millions of dollars as institutional sentiment improved. ETH perpetual open interest stabilized near $12.5 billion, with funding rates hovering around neutral. Analysts compared the setup to the Pectra post-fork structure, which saw meaningful follow-through over subsequent months, though macro uncertainty—especially U.S.–China tariff developments—capped near-term breakout momentum.

Long-term, Fusaka strengthens Ethereum’s rollup-as-a-service strategy by keeping verification lightweight and widening data bandwidth for rollups, supporting a path where even consumer-grade hardware can run full nodes and validators. This helps preserve Ethereum’s decentralization as demand scales, while EIP-1559’s fee-burn mechanism continues to link network usage to ETH value accrual. Regulatory developments such as MiCA 2.0 in the EU are expected to catalyze institutional experiments with tokenized assets and on-chain financial infrastructure, potentially accelerating adoption of P-256-based authentication flows enabled by Fusaka’s cryptographic upgrades. Analysts caution, however, that Layer-2 fragmentation and lack of unified standards may create efficiency losses without stronger cross-rollup interoperability—an active area of research in the Ethereum ecosystem.

Sentiment across the developer and research community converges on a common theme: Fusaka is not a flashy upgrade, but a foundational one. Ethereum researchers describe Fusaka as quietly transformative—scaling the network by reducing verification burden rather than relying solely on added layers. Client maintainers emphasize that Fusaka’s improvements to blob markets and validator workloads prepare Ethereum for much larger rollup throughput in 2026 and beyond. Market strategists note that if the broader macro backdrop stabilizes and institutional flows continue to rise, Fusaka’s data-capacity expansion could form the technical base for Ethereum’s next growth cycle. Overall, Fusaka reinforces Ethereum’s trajectory toward a $1 trillion-scale infrastructure platform by the end of the decade, contingent on continued execution and resilience in the face of global economic volatility.