Each market's spread is set from how much it actually costs you to get adversely selected, measured as the average move against you right after a fill, plus the profit margin you want. So toxic, fast-moving markets get wider spreads and quiet ones get tighter spreads automatically. The edge is correctly pricing the risk you take on every quote across very different Polymarket markets, rather than using one fixed spread everywhere.
Markets on Polymarket where adverse-selection-adjusted spread sizing is the natural play:
