Flashbots acquires Beaverbuild
Flashbots has acquired Beaverbuild, the top builder for Ethereum. As much as 70% of block production can be won by them now.
Flashbots has acquired Beaverbuild, the top builder for Ethereum. As much as 70% of block production can be won by them now.
Currently, there are 2 builders who win almost all the real-time MEV-Boost auctions. Further, the top builder wins roughly half of the auctions, the second wins roughly four-tenths, and a long tail of builders shares the remaining tenth.
But Dr. Blockrotator, what about this post straight from “The MEV Letter”?
Beaverbuild → BuilderNet by Flashbots announces that beaverbuild is retiring their centralized block builder to work full-time on BuilderNet as a development partner to accelerate its roadmap.
— Forum Post by Shea Ketsdever
buildernet.txt by beaverbuild announces the retirement of their legacy block builder to co-develop BuilderNet in order to ensure block building is decentralised, uncensorable, and neutral.
Why Top Builders Bid Less (and Still Win More): Auction Strategy Differences in Ethereum’s PBS
In Ethereum’s Proposer-Builder Separation (PBS) ecosystem, not all builders play by the same rules: that’s by design. A core driver of this imbalance is the “information difference” among builders, largely due to access to private order flows. Builders with better access to private transactions can construct higher-value blocks, giving them a crucial edge in the MEV-Boost auctions.
But here’s the twist: the builders with the most valuable blocks tend to bid less aggressively than their lower-valued counterparts and yet, they win more often.
What Does “Less Aggressive” Really Mean?
Let’s clarify: when we say a builder bids “less aggressively,” we don’t necessarily mean they submit a lower absolute bid. Instead, we’re talking about bidding a smaller percentage of their block’s total value to the proposer.
So why can top builders afford to do this?
Because their blocks are more valuable to begin with. Thanks to private order flows, they have higher block valuations and can retain a larger share of the profits, even while bidding less proportionally.
The top 3 builders, who account for over 90% of blocks, consistently bid under 80% of their block value.
In contrast, lower-tier builders typically bid a higher percentage but still lose.
Despite bidding less proportionally, dominant builders win more often — a counterintuitive outcome if we expect a “fair” public auction.
The Impact of Private Order Flow on Ethereum’s Auction Market
Stronger builders—those with superior access to private order flow—can bid less and still consistently win blocks. This dynamic has two major consequences:
- Reduced Proposer Revenue
Dominant builders capture a larger share of each block’s value, which means proposers earn less.
In highly concentrated markets, builder margins increase
In more competitive environments, builder margins decrease.
This undermines the original goal of Proposer-Builder Separation (PBS)—to maximize rewards for Ethereum stakers.
- Centralization Through Positive Feedback Loops
The deeper issue lies in a self-reinforcing cycle:
Builders who win more blocks attract more private order flow.
More private flow →
higher expected block value →
more frequent wins →
even more private flow.
Why This Breaks the Ideal PBS Model
In a perfectly transparent market, all builders would bid close to 100% of their block value to proposers, leaving little margin. But the reality is far from this ideal. In this information asymmetry (largely due to private order flow), powerful builders don’t have to bid that much to win.
This is why we have been working on XGA, eXtensible Gas Auctions (www.xga.com), with our launch in January 2026 you can sign up to find out more about how it works and to see how it will improve the Ethereum network at: https://forms.gle/GHiHqo6z8rMsK8CXA
