Exchange-Traded Options, also known as 'listed options', provide many benefits that distinguish them from over-the-counter (OTC) options. Because exchange-traded options have standardized strike prices, expiration dates, and deliverables (the number of shares/contracts of the underlying asset), they attract, and accommodate, larger numbers of traders. OTC options usually tend to have customized provisions.This gives listed option contracts more liquidity than OTC option contracts. In addition, because exchange members must post margin when trading listed options - but not when trading OTC options - there is less risk involved for the buyer of a listed option contract.Listed options also offer greater price transparency than OTC options do. The bid/ask spread is typically narrower for listed options than it is for OTC options because there are more market makers competing for customer order flow in the listed marketplace. As a result, it is easier for buyers and sellers of listed options to get fair prices on their trades.