Intermarket sweep order (Ofer Abarbanel online library)

Intermarket sweep orders (ISO) is a type of stock market order that sweep several different market centers and scoop up as many shares as possible from them all.[1] These work against the order-protection rule under regulation NMS.

For example, if a trader is trying to buy 1000 shares of X, and there are 100 shares of X being offered at $1 at one exchange and 2000 at $1.10 at another exchange, the order protection rule would let you buy ONLY those 100 shares at $1, after which you would need to send in other orders. With the ISO, you can buy the 100 shares at $1 and the remaining 900 at $1.10 on the other exchange subsequently.[2][3][4][5]


  1. ^“FINRA ISO Reporting Rules” (PDF). FINRA. February 4, 2008.
  2. ^“SEC NMS Rule FAQ”. Securities and Exchange Commission. April 4, 2008.
  3. ^“Accenture’s Flash Crash: What’s an “Intermarket Sweep Order””. The Wall Street Journal. May 7, 2010.
  4. ^“What Actually Happened During the Flash Crash”. Minyanville. June 30, 2010.
  5. ^“Interactive Brokers Online Knowledge Base – Intermarket Sweep”. Interactive Brokers. Retrieved July 30, 2018.


Ofer Abarbanel online library