IB capped cancelletion fee, but I found its commisiion fee suddenly jumped like NFLX. normally 100lot costs me 100~200bucks, but now sometimes greatly exceed this number. and it varies time from time, strike to strike, instrument to instrument. I am wondering why the same strike today I need pay this commission, and another time, I need pay higher commision, it is very unpredictable. not like stocks, 200shares cost 1buck. so i can know before. any option house with fixed rate, no cacelletion fee,low reasonable commission fee? I trade options mainly, ocassionally individuals stocks and futures.