Some markets are logically linked: for example 'A wins overall', 'A wins region R', and 'region R goes A's way' must obey the rule that the chance of A overall equals the chance A wins R times the chance R happens. When the separately-listed prices break this rule, you buy the underpriced combination and sell the overpriced pieces so the trade pays for itself. The edge is that nobody checks whether these related markets stay consistent with each other.
Markets on Polymarket where triangular arbitrage across linked markets is the natural play:
