Options Glossary

Margin / Margin requirement: The minimum equity required to support an investment position. To buy on margin refers to borrowing part of the purchase price of a security from a brokerage firm.
Mark-to-market: An accounting process by which the price of securities held in an account are valued each day to reflect the closing price or closing market quotes. As a result, the equity in an account is updated daily to reflect current security prices properly.
Market maker: An exchange member on the trading floor who buys and sells options for their own account and who has the responsibility of making bids and offers and maintaining a fair and orderly market. See also Specialist / specialist group / specialist system.
Market maker system (competing): A method of supplying liquidity in options markets by having market makers in competition with one another. As an alternative to a specialist system, they are also responsible for making fair and orderly markets in a given class of options.
Market order: A trading order placed with a broker to immediately buy or sell a stock or option at the best available price.
Market quote: Quotations of the current best bid/ask prices for an option or stock in the marketplace (an exchange trading floor). The investor usually obtains this information from a brokerage firm. However, for listed options and stocks, these quotes are widely disseminated and available through various commercial quotation services.
Market-not-held order: A type of market order that allows the investor to give discretion to the floor broker regarding the price and/or time of trade execution.
Market-on-close order (MOC): A type of option order that requires that an order be executed at or near the close of trading on the day the order is entered.
Married put strategy: The simultaneous purchase of stock and put options representing an equivalent number of shares. This is a limited risk strategy during the life of the puts because the stock can always be sold for at least the strike price of the purchased puts.
MCRY: Nasdaq MRX, LLC
MIAX: Miami Options Exchange
Model: A mathematical formula used to calculate the theoretical value of an option. See also Black-Scholes formula.
MPRL: MIAX PEARL, LLC
Multiple-listed / multiple-traded option: Any option contract listed and traded on more than one national options exchange. See also Fungibility.