The term discretionary order refers to instructions sent to a broker that provides latitude to determine the best price for a transaction. In some markets, discretionary orders allow traders to provide and take liquidity using a single order.
Explanation
The most common orders placed by traders provide very specific instructions to a broker regarding the price to buy or sell a security. In some markets, it is possible to provide the broker with some limited discretion. That being said, the broker's objective is to provide the trader with the best possible price for their securities. A discretionary order may also allow the broker to vary the timing of the transaction.
In some markets, a discretionary order may consist of a limit order that also has an optional value that can be used to vary the price range of the order. The market would only see the limit price. Since there is less transparency in these markets, it's difficult to determine the best possible bid and offer prices. For example, a trader may be able to place a limit order price of $10.50, allowing the broker $0.05 discretion.
The term market peg order refers to those that follow the best bid, when selling a security, and the best offer, when buying a security. Market peg orders follow the opposite side of the market than primary peg orders.
The term National Best Offer refers to the lowest available ask price, which is a consolidated value from all of the national stock exchanges. The National Best Offer is the lowest price sellers are willing to accept for a security such as a stock.
The term National Best Bid refers to the highest available bid price, which is a consolidated value from all of the national stock exchanges. The National Best Bid is the maximum price buyers are willing to pay for a security such as a stock.
The term market order refers to instructions sent to a broker to buy or sell a security immediately at the best available price. Since there are no restrictions on the selling or purchase price of the security, a market order is oftentimes immediately executed.
The term limit order refers to instructions sent to a broker to buy or sell securities at a specific price or better. Since a limit order is not a market order, there is no guarantee the transaction will occur.
The term day order refers to broker instructions to buy or sell a security that automatically expires at the end of the trading day if not executed. Unless specified by the investor, the default orders to buy and sell stocks at most brokerage houses are day orders.
The term primary peg order refers to those that follow the best bid, when buying a security, and the best offer, when selling a security. Primary peg orders allow traders to get the best possible price as a security moves within certain boundaries.
The term long position refers to the practice of buying a security with the expectation that its value will increase over time. Long positions apply to stocks, commodities, currency as well as options.
The term alligator spread is used to describe a combination of puts and calls that are not profitable due to relatively high commissions. Alligator spread refers to the investor's position being "eaten alive" by the commissions.
The term dark pool refers to a private forum or securities exchange used by traders. A dark pool is not accessible to the investing public, and the name describes the lack of transparency that exists in these exchanges.
The term Do Not Reduce refers to broker instructions to not lower the price of an order by the amount of an ordinary cash dividend on the ex-dividend date. Do Not Reduce orders typically apply when the price on an order is under market, and accompanied by Good-Til-Canceled instructions.
The term midpoint peg order refers to those that are aligned with the average of the National Best Bid and National Best Offer. Midpoint peg orders can be used by traders to discover hidden orders and those in what are referred to as dark pools.
The term Not-Held refers to broker instructions that permit discretion in order to obtain the best possible price on a security. Not-Held orders are typically associated with market or limit orders.
The term order book is used to describe a listing of buyers and sellers interested in exchanging certain securities. Oftentimes an electronic matching engine is used to determine which transactions can be successfully executed.