MEV in Binance Builder

Abstract: We study the builder-driven MEV arbitrage on BNB Smart Chain (BSC). BSC's Proposer--Builder Separation (PBS) adopts a leaner design: only whitelisted builders can participate, blocks are produced at shorter intervals, and private order flow bypasses the public mempool. These features have long raised community concerns over centralization, which we empirically confirm by tracing arbitrage activity of the two dominant builders from May to November 2025. Within months, 48Club and Blockrazor produced over 96\% of blocks and captured about 92\% of MEV profits. We find that profits concentrate in short, low-hop arbitrage routes over wrapped tokens and stablecoins, and that block construction rapidly converges toward monopoly. Beyond concentration alone, our analysis reveals a structural source of inequality: BSC's short block interval and whitelisted PBS collapse the contestable window for MEV competition, amplifying latency advantages and excluding slower builders and searchers. MEV extraction on BSC is not only more centralized than on Ethereum, but also structurally more vulnerable to censorship and weakened fairness.