A September preprint found that professional automated market makers (PropAMMs) had a reference-relative execution cost proxy of 0.26 basis points for quiet-market SOL/USDC swaps, significantly lower than 2.59 basis points for public automated market makers (AMMs). The study, covering September 1, 2025, through August 31, 2026, also reported PropAMMs' two-second gross maker markouts at +0.37 basis points, while public AMMs were at -0.22 basis points. The researchers noted that lower swap costs do not guarantee positive liquidity provider (LP) returns, and passive depositor returns require separate accounting.