MEV, Pre-confirmations & Block Building
MEV is evolving from a simple front-running problem into a fundamental scaling constraint. The 2026 frontier: L2 spam caused by MEV bots consuming majority of throughput, and pre-confirmations as an application-layer solution to UX without waiting for block inclusion. (→ [[ethdenver]])
MEV on L2s: The Spam Crisis (Daniel Marzec / Flashbots)
The problem: 50%+ of gas on L2s is consumed by MEV bot spam — bots attempting ~350 failed transactions for every successful arbitrage. A $0.12 arbitrage costs 130M gas to execute — a 650× efficiency gap.
Root causes:
- Transaction expressivity: no native conditional logic → bots must broadcast many speculative transactions
- Private mempools: bots can’t see each other’s activity → no signal, pure brute force
- Cheap fees: at 1¢/attempt, spam is economically rational
- No efficient auctions: no mechanism to bid for MEV rights → blind competition on every block
Impact: L2 throughput capacity is being consumed by economically wasteful competition. This caps the effective TPS available for real user transactions.
Solutions:
- Programmable privacy via TEEs: searchers operate inside trusted execution environments with full transaction visibility, extract value more efficiently, drastically fewer attempts
- Explicit auctions: bid for MEV rights upfront rather than spamming; auction clears at competitive price; total attempts collapse; winners execute once
Early TEE-based results: searchers with full TX data extract same value with far fewer transactions. MEV auctions are not a luxury — they’re a scaling requirement.
Pre-confirmations (Murat Akdeniz / Primev)
What they are: Credible, cryptographically enforceable commitments from block builders that a specific transaction will be included in a specific block.
Economics: Builders post 5+ ETH stake (slashable); commitments are economically enforced even before ZK/cryptographic enforcement. If a builder commits and then doesn’t include, they’re slashed.
Current scale (Jan 2026):
- 70%+ of block building power participates
- 90%+ relay participation
- 6,000+ validators on network
- 120ms effective transaction confirmation time
- 8% of blocks carry pre-confirmations
2026 vision: Pre-confirmations become a first-class Ethereum protocol primitive (like blobs and gas). Enables:
- Instant wallet UX (confirmation before block close)
- Synchronous composability between L1 and L2
- The “instant” button in wallet UX: “hit the button and it’s done by the time you lift your finger”
Pre-confirmations are not a replacement for L2s — they enable asynchronous composability across the L1/L2 stack when combined with rollups.
EIP-7732 (ePBS): Protocol-Level Block Structure
EIP-7732 separates the execution payload from the consensus block. This is the protocol-level foundation for all advanced block building. (Terence Tsao / Ethereum Foundation)
Current bottleneck: Execution payload dominates block size (90–95%). Consensus is only 5–10%. But both are processed on the same tight timeline (2 seconds for the proposer to act).
The pipeline ePBS enables:
| Slot time | Event |
|---|---|
| 0–4s | Proposer commits to validator set |
| 5–6s | Payload builder reveals execution payload |
| 7–9s | Separate attestation committee (512 validators) validates payload |
| 9–12s | Final finalization |
Benefits:
- Attesters now have 9–12 seconds (vs. 2 seconds) to download and verify
- ZK provers get more time for proof generation within each slot
- Enables slot auctions, MEV burning, and advanced validator market structures
- Foundation for much shorter slot times (4 seconds target)
Proprietary AMMs (Prop AMMs) on EVM (Fahim Ahmed / Flashbots)
Context: Proprietary AMMs captured 73% of Solana volume by giving market makers control over their own price curves. Now landing on EVM (Base) despite historically higher gas.
Key design: Pricing contracts + oracle fallback; spreads widen for risky traders and imbalanced pools; negative spreads prevented by design. Wintermute and AlphaLQD are early deployments.
Why possible on EVM now: Batch updates (one transaction updating multiple price curves) are cheaper than per-order CLOB updates.
Best fit: Tokenized stocks and RWAs requiring cheap, frequent price updates without the latency trade-offs of on-chain CLOBs.
Continuous Clearing Auction (Dingyue Liu / Uniswap Labs)
A new token distribution mechanism that eliminates the gaming of traditional airdrops and fixed-price sales:
- Problem with existing mechanisms: Airdrops get immediately dumped (66%), fixed-price auctions create gas wars on timing, insider allocations built-in
- CCA mechanism: Demand curves aggregated across all participants; algorithm finds one uniform clearing price per block; repeated continuously across the auction period
- Results (Aztec CCA): 99% of users contributed under 100K, 17,000+ unique bidders, $60M raised with no insider advantage
Weiroll: DeFi Execution Primitive (Colin Platt / Makina)
Lightweight on-chain VM for sequential DeFi execution:
- Chains outputs across arbitrary protocols: Uniswap swap → Pendle deposit → Morpho borrow in one atomic transaction
- Single revert protects the entire chain; no race conditions; no multi-tx gas bloat
- Merkle-tree whitelisting: approve specific protocol/asset combinations for vault strategies
- Can execute cross-chain (e.g., Hyperliquid perps via EVM precompiles without bridging)
- Used by Machina for multi-chain institutional vaults
Weiroll and Brevity: Interpreted EVM Scripting Language serve similar use cases from different directions — Weiroll is opinionated about DeFi composition; Brevity is more general-purpose.
Connections
- Ethereum Scaling Roadmap — ePBS is in Glamsterdam (next fork); pre-confirmations are the application-layer complement; MEV spam caps effective L2 TPS
- Ethereum Real-Time Blockspace — 100ms mini-blocks eliminate MEV differently (timing gap too short); complementary approach to pre-confirmations
- Distributed Block Building — BuilderNET, TEE-based building are the infrastructure layer; this page covers the UX and market design layer
- Ethereum Staking Dynamics — MEV is ~30bps of validator yield; ePBS separates the payment pathway from the consensus pathway
- Brevity: Interpreted EVM Scripting Language — Brevity and Weiroll are parallel approaches to composable DeFi execution
Open Questions
- At what MEV auction participation threshold does L2 spam materially decline — or does it require mandatory auctions?
- Will pre-confirmations remain an application-layer feature or get enshrined in protocol (as 2026 roadmap suggests)?
- Do prop AMMs fragment liquidity from public AMMs, or do they draw in new flow that doesn’t currently exist on-chain?
- How does ePBS interact with real-time mini-blocks (ETHGas) — can both run on the same block structure?