Lightspeed Solana’s Block Building Battle: Jito BAM vs. Harmonic
Feb 19, 2026
Sam Schubert, a Blockworks researcher who led the Solana block-building investigation, and Carlos, a Blockworks Solana analyst, unpack the Jito BAM vs Harmonic clash. They discuss block packing, transaction ordering, MEV and fee impacts. They examine validator client shifts, MCP/Alpenglow protocol fixes, and the future move toward application-controlled execution.
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Block Building Shapes Market Microstructure
- Block building architecture directly shapes market microstructure and trading behavior on Solana.
- Inconsistent block formats across leaders make optimal quoting and market-making much harder.
Jito BAM’s Privacy-First Sequencing
- Jito BAM uses TEEs to keep transaction ordering private and defaults to priority-fee-per-CU ordering.
- BAM plans plugins for application-controlled execution to enable features like prioritizing cancels.
Harmonic’s Aggregation Marketplace
- Harmonic aggregates multiple block builders so validators can pick blocks by revenue or other preferences.
- Harmonic positions itself as creating a marketplace for block building rather than a single sequencer.