Weather Bot — Episode 13: The Fee Change, the Ghost Trade, and Where Things Stand Now
Two problems hit at the same time. One was announced publicly. The other I only found because a position showed up in my Polymarket wallet that my bot didn't know about. What This Post Covers A fee structure change that forced me to rethink how my bot places orders, a ghost trade that revealed three separate bugs in my position tracking, and a price analysis that accidentally confirmed my 48-hour buy limit was landing on the optimal entry window. Plus where the numbers actually stand right now. The Fee Change On March 30, Polymarket expanded taker fees to weather markets. Previously only crypto and sports had fees. Now every category except geopolitical events gets charged. The fee is dynamic — highest around 50% probability ($0.50 price), dropping toward zero at the extremes. For weather markets where I'm buying at $0.15-$0.25, the effective rate is about 1.00%. But the fee only applies to taker orders. There are two types on Polymarket: Maker orders (GTC/limit)...