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The NASDAQ OMX Group owns and operates 26 markets, making them the largest exchange company in the world.


Currency: US Dollar (USD)

Holiday Calendar
Trading Hours

Order Types

Note: not all order types are available for every gateway.

  • Inside Limit Buy/Sell→ShortSell (Day)

  • Limit Buy/Sell→ShortSell (Day/FOK/IOC)

  • Limit-on-Close (LOC) & Limit-on-Open (LOO) Buy/Sell→ShortSell

  • Market Buy/Sell→ShortSell (Day/FOK)

  • Market-on-Close (MOC) & Market-on-Open (MOO) Buy/Sell→ShortSell

  • Pegged Midpoint/Market/Primary Buy/Sell→ShortSell (Day)

  • Reserve Limit Buy/Sell→ShortSell (Day)

  • Stop Limit Buy/Sell→ShortSell (Day)

Available ATS

  • ARCX: NYSE Arca

  • ATD: Automated Trading Desk Dark Pool

  • BARC: Barclays Capital Dark Pool


  • BIDS: BIDS Dark Pool

  • BLOC: BLOCK Dark Pool

  • BOFA: Bank of America Dark Pool

  • BATY: BATS-Y Exchange

  • CBSX: CBOE Stock Exchange

  • CSD: Credit Suisse Crossfinder+

  • DARK: Consolidated Dark Pool

  • DBA: Deutsche Bank Dark Pool

  • EDGA: Direct Edge

  • EDGX: Direct Edge

  • FIDE: Fidelity Dark Pool

  • GETC: Getco Dark Pool

  • IEX: IEX

  • KNGM: Knight Capital Group


  • MSCO: Morgan Stanley Dark Book




  • NSX: National Stock Exchange

  • NTHK: Instinet Nighthawk Dark Pool


  • SGMX: Sigma X Dark Pool

  • SPDR: SpeedRoute Dark Pool

  • UBS: UBS Dark Pool

Basic Market Rules

  • Lot Size: 100 shares.

  • Tick Size: varies by price and security.

  • Short Sale Rules: naked short sales are prohibited, a locate must be obtained prior to executing a short sell.

  • Circuit Breakers: imposed under conditions defined on the Market Wide Circuit Breaker page.

Auction Mechanisms


The pre-opening session runs from 07:00 - 09:30. During this session, orders can be entered and cancelled but no matching will occur. The Calculated Opening Price (COP) is displayed and continuously updated. At the open (09:30) all matching orders are executed at a single opening trade price with remaining orders left on the continuous limit order book.


The closing price is defined by the following closing auction mechanism.

Auction means an auction conducted in a trading platform with respect to qualifying orders to determine the auction price pursuant to the following process and priority:

  • a) The indicative clearing price range is bounded on the far side by the price at which the MOC, LOC, and IO orders would clear with only each other.

  • b) The indicative clearing price range is bounded on the near side by the price at which the Nasdaq Closing orders and continuous orders (excluding volume that is available only by order delivery) would clear.

  • c) If the Nasdaq closing cross price is selected and fewer than all Nasdaq Closing Orders and all continuous orders that are available for automatic execution in the Nasdaq Market Center would be executed, the system executes orders in the following priority:

    • i. MOC Orders, with time as the second priority;

    • ii. LOC orders, limit orders, IO orders, displayed quotes, and reserve interest that are priced more aggressively than the Nasdaq Closing Cross Price;

    • iii. LOC orders, displayed interest of limit orders, and displayed interest of quotes at the Nasdaq Closing Cross price with time as the second priority;

    • iv. Reserve interest and IO orders at the Nasdaq Closing Cross price with time as the second priority.

Auction Periods

The following periods affect only order entry for participation in the closing auction. There is continuous trading from 09:30 - 16:00 during which regular (non-imbalance) orders will be matched.

1. Pre-Imbalance (09:30:01 - 15:50)

  • Continuous trading occurs, where bids and offers may be entered, amended, or cancelled

  • Market-On-Close (MOC) or Limit-On-Close (LOC) orders may be entered, amended, and cancelled

  • No imbalance orders will be matched

2. Post-Imbalance (15:50 - 16:00)

  • Imbalance-only (IO) orders can be entered

  • Continuous trading occurs, where bids and offers may be entered, amended, or cancelled

  • MOC, LOC, or IO orders cannot be cancelled or modified

3. Closing Cross Price (16:00:00 - 16:00:05)

  • Closing auction is conducted

  • Auction imbalance orders are matched at the Closing Cross

Order Types: Limit-on-Close, Market-On-Close, and Imbalance Only orders are eligible to participate in the Closing Auction.

For more information on the auction mechanisms on the NASDAQ Stock Exchange, see the Nasdaq Market Center Systems Description document.

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