PropAMMs lower Solana trade costs, and public pool returns crash

A trader can get a better Solana (SOL) swap price while a passive pool depositor remains exposed to traders picking off stale quotes, and a Sept. 29 preprint measures that divide.For quiet-market SOL/USDC fills, propAMMs, pools controlled by professional operators, had a reference-relative execution cost proxy of 0.26 basis points versus 2.59 for public automated market makers (AMMs).The study covers Sept. 1, 2025, through Aug. 31, 2026, with shorter Base and Monad samples. It weights fills by notional against Bybit's size-weighted top-of-book USDT microprice, converted with its USDC/USDT midpoint. Its authors list ETH Zurich and Category Labs affiliations.A swapper wants more tokens for the same input, while a depositor supplies the inventory others trade against and needs compensation for the risks that inventory carries. Low execution cost can attract the first participant without being a sufficient investment case for the second.Swap prices and depositor returns on SolanaAcross its Solana sample, the paper reports two-second gross maker markouts of +0.37 basis points for propAMMs and −0.22 for public AMMs. A markout compares a fill with a later reference price, and a positive n...