Ethereum is preparing what may be its most consequential hard fork since The Merge. Code-named Glamsterdam and targeting mid-2026 activation, the upgrade aims to dismantle the concentrated power structure that has quietly taken root in Ethereum's block production pipeline while simultaneously unl...
"If a small number of builders dominate, they could still censor transactions or extract outsized profits from users." — Vitalik Buterin, Ethereum Co-Founder, March 2026 Blog Post on Block Builder Centralization
Ethereum is preparing what may be its most consequential hard fork since The Merge. Code-named Glamsterdam and targeting mid-2026 activation, the upgrade aims to dismantle the concentrated power structure that has quietly taken root in Ethereum's block production pipeline while simultaneously unlocking parallel transaction execution at the protocol level.
The stakes are existential. Today, the top three block builders control 85.9% of all Ethereum blocks and capture 86.8% of all MEV (Maximal Extractable Value). The Herfindahl index for Ethereum's block builder market stands at 3,186 — 2.5 times more concentrated than mining was before the 2022 Merge. Glamsterdam's headliner proposal, EIP-7732 (Enshrined Proposer-Builder Separation), would hardcode the separation of block proposers from block builders directly into Ethereum's consensus layer, replacing the fragile off-chain relay infrastructure that currently mediates this process.
Meanwhile, EIP-7928 (Block-Level Access Lists) would enable the first true parallel execution of the Ethereum Virtual Machine, potentially reducing gas fees by up to 78% and opening the door to a 200-million gas limit — more than quadruple today's effective capacity. The upgrade arrives at a paradoxical moment: Ethereum is processing record activity (2 million daily active addresses, 40 million smart contract calls per day) while generating less than $10.3 million in monthly fees and watching ETH trade 30% below its August 2025 highs. Glamsterdam is Ethereum's bid to resolve this contradiction.
Ethereum's transition to proof-of-stake was supposed to democratize block production. Instead, it created a new oligopoly. Under the current system, validators outsource block construction to specialized builders through MEV-Boost, an off-chain relay system developed by Flashbots. Builders compete by assembling the most profitable blocks — often by front-running, sandwiching, or reordering user transactions to extract MEV.
The concentration is severe. According to research from Decentralized Thoughts and on-chain analytics, three builders — Beaver Build, rsync-builder, and Titan Builder — now assemble the vast majority of Ethereum blocks. This level of concentration introduces systemic risks: censorship capability, single points of failure, and an extractive economic relationship between builders and users.
The problem is not theoretical. Researchers have documented that builders routinely include sandwich attacks — placing buy and sell orders around a user's trade to profit from the price impact — as a primary revenue strategy. Users pay more for every swap, every lending action, every bridge transaction. The total value extracted through toxic MEV runs into hundreds of millions of dollars annually, functioning as a hidden tax on Ethereum's user base.
Vitalik Buterin's March 2, 2026 blog post laid out the strategic response: a three-phase approach combining ePBS (Glamsterdam), FOCIL inclusion lists (Hegota), and ultimately encrypted mempools to create what he called a "neutral zone" in block production.
At the consensus layer, EIP-7732 is the centerpiece of Glamsterdam. It replaces the current off-chain relay model with a protocol-native commit-reveal mechanism. Here is how it works:
Current system: Validators connect to third-party relays (Flashbots, BloXroute, etc.) that act as trusted intermediaries between builders and proposers. Builders submit blocks to relays. Relays verify blocks and pass headers to proposers. Proposers blindly sign the most profitable header. The relay reveals the full block.
Post-ePBS system: Builders commit to block contents directly on the beacon chain. Proposers select builder commitments through a standardized auction. The protocol enforces builder commitments at the consensus layer — no relay trust required. Invalid or absent blocks are handled by protocol-level slashing and fallback mechanisms.
The implications are profound. First, it eliminates relays as trusted intermediaries — a single point of failure and censorship vector. Second, it standardizes MEV handoff rules, creating a level playing field enforced by code rather than reputation. Third, it opens the path for future anti-censorship mechanisms like FOCIL (Fork-Choice Enforced Inclusion Lists), proposed for the subsequent Hegota upgrade, which would allow randomly selected validator committees to force inclusion of censored transactions.
If ePBS restructures who builds blocks, EIP-7928 restructures how blocks are executed. Today, every Ethereum node processes transactions sequentially — one after another — regardless of whether they touch the same state. This serial execution model is a fundamental bottleneck.
EIP-7928 introduces Block-Level Access Lists (BALs): a new block header field that records every account and storage slot accessed during execution, along with post-execution values. Block producers pre-calculate which transactions can run simultaneously without conflict, and clients allocate non-conflicting transactions across multiple CPU cores.
The technical architecture enables four critical capabilities:
The overhead is manageable. Research from Ethereum's core development community estimates an average BAL size of approximately 70 KiB per block — meaningful but acceptable given the performance gains. Multiple client teams, including Geth, Nethermind, Besu, and Erigon, are actively prototyping implementations.
This is not an incremental optimization. It is a fundamental re-architecture of how the EVM processes computation, and it directly enables the gas limit increases and fee reductions that Glamsterdam promises.
Complementing the headline EIPs, Glamsterdam includes a package of at least 10 gas repricing proposals anchored by EIP-7904 (General Gas Cost Repricing). The premise is straightforward: Ethereum's current gas costs for many opcodes were set years ago and no longer reflect actual computational costs measured by modern client benchmarks.
EIP-7904 realigns opcode pricing with empirical performance data, reducing costs for overpriced operations and increasing costs for underpriced ones. The net effect for users: a projected 78.6% reduction in gas fees for both simple transfers and complex smart contract interactions.
This arrives at a moment when Ethereum mainnet gas fees have already collapsed to historic lows. As of March 12, 2026, Etherscan's gas tracker shows average prices at 0.196 Gwei, with intraday lows touching 0.055 Gwei. ERC-20 transfers cost $0.01-$0.02. A Uniswap swap costs approximately $0.14. These represent a 90% year-over-year decline from March 2025 levels of approximately 6 Gwei.
The gas limit itself is targeted to increase to 200 million — more than quadrupling effective throughput. Combined with parallel execution, this positions Ethereum L1 to handle significantly more activity before congestion-driven fee spikes occur.
Glamsterdam arrives amid Ethereum's most confounding period. The network has never been busier — and has rarely been less profitable.
Record activity metrics (February-March 2026):
Collapsing value capture:
The data tells a stark story. Ethereum's successful scaling — through Dencun's blob transactions in 2024 and Fusaka's PeerDAS expansion in late 2025 — has shifted execution to Layer 2 networks so effectively that the base layer now functions primarily as a settlement layer at 46% utilization. Base, Coinbase's L2, now generates approximately three times Ethereum's own protocol revenue.
This is the economic context that makes Glamsterdam more than a technical upgrade. Parallel execution and gas repricing aren't just about speed — they're about making L1 competitive enough to attract direct activity back to mainnet while simultaneously reducing costs for the L2s that settle on it.
The L2 ecosystem is watching Glamsterdam closely. The Base development team published a detailed analysis of Glamsterdam proposals, selecting six non-headliner EIPs they consider most impactful across three categories: blob scaling, gas repricing, and builder UX improvements.
Base's strategic position is notable. In February 2026, Coinbase announced that Base would migrate away from the OP Stack to a unified, self-managed system called base/base — an independence declaration from the Optimism ecosystem. This move, combined with Glamsterdam's blob capacity expansion, positions Base to optimize its L2 economics independently while benefiting from lower L1 settlement costs.
The broader L2 landscape faces a consolidation reckoning. Among the proliferating rollup ecosystem, only a handful generate meaningful economic activity. Glamsterdam's blob scaling and gas repricing will lower L2 operating costs further, but this primarily benefits dominant platforms like Base, Arbitrum, and Optimism while doing little for the long tail of under-utilized L2s.
Glamsterdam is aspirationally targeting a June 2026 mainnet activation, though developers emphasize this remains flexible. The Ethereum Foundation DevOps team has tested three key EIPs on Devnet-4 and is currently focused on Devnet-5 testing.
The timeline risk is non-trivial. EIP-7732 requires changes across both the execution and consensus layers. EIP-7928 introduces a new block header field and demands cross-client coordination among four major client teams. Public testnets and dual audit phases are outlined for early-to-mid 2026, creating the earliest realistic path toward safe activation.
The subsequent Hegota upgrade — featuring FOCIL (EIP-7805) for censorship resistance — is tentatively scheduled for late 2026, completing the two-fork cycle that Ethereum has committed to for the year.
Glamsterdam is Ethereum's most structurally ambitious upgrade since The Merge, targeting both the economic architecture (who builds blocks and captures value) and the execution architecture (how transactions are processed).
Builder centralization is Ethereum's most underappreciated systemic risk. Three builders control 85.9% of blocks. EIP-7732 eliminates the trusted relay layer and hardcodes proposer-builder separation into consensus — a necessary but insufficient step toward decentralization.
Parallel EVM execution (EIP-7928) is a paradigm shift, enabling multi-core transaction processing and potentially 78% gas fee reductions. This is not optimization — it is re-architecture.
Ethereum's value capture crisis gives Glamsterdam existential urgency. Record network activity generating just $10.3M in monthly fees while L2s like Base capture 3x the protocol revenue exposes a fundamental economic misalignment.
Timeline risk is real. June 2026 is aspirational. Cross-client coordination, dual audits, and the sheer complexity of concurrent consensus and execution layer changes could push activation into H2 2026.
For investors: Glamsterdam's success or failure will likely determine whether Ethereum resolves its price-activity divergence. A network processing 2 million daily active addresses and 40 million smart contract calls should not be generating $10M in monthly fees. Glamsterdam is the technical prerequisite for fixing that equation.
Ethereum stands at an inflection point. Its scaling roadmap has succeeded — perhaps too well. By making Layer 2 transactions so cheap that users rarely touch mainnet, Ethereum has hollowed out its own revenue model. Gas fees at 0.196 Gwei and 46% block utilization tell the story of a settlement layer that hasn't yet figured out how to monetize its settlement services.
Glamsterdam attempts to address this from multiple angles simultaneously. Enshrined proposer-builder separation tackles the centralization risk that could undermine the network's credibility as a neutral settlement layer. Parallel execution and gas repricing make L1 itself more competitive, potentially attracting activity back from L2s while also reducing L2 settlement costs. The gas limit increase to 200 million creates headroom for growth before congestion returns.
But the upgrade also represents a calculated gamble. Making Ethereum faster and cheaper does not automatically translate to more revenue. If parallel execution simply enables more activity at lower per-unit costs, the value capture problem persists. The resolution likely depends on what happens after Glamsterdam — whether the FOCIL mechanisms in Hegota, combined with growing L2 activity, create enough blob demand to establish a sustainable fee market.
What is clear is that the status quo is untenable. A $233 billion network generating $10 million in monthly fees while three builders control 86% of block production is not a stable equilibrium. Glamsterdam is Ethereum's most important upgrade since it stopped mining — and the market is not yet pricing in the implications.