Features and Functionality

PSX has transitioned to a Price Setter Pro Rata algorithm for all symbols. The new PSX model provides an incentive for greater displayed size while also encouraging participants to aggressively compete on price.

Price Setter Pro Rata

Under the new Price Setter Pro Rata priority structure, orders that set the PSX Best Bid or Offer (PSX BBO) are guaranteed a 40% allocation when incoming marketable orders are executed. The remaining 60% of a given order is executed against resting orders via a size pro rata allocation. If there is no Price Setter at a given price level, incoming orders are executed against resting orders via a size pro rata allocation.

  • Orders must be round lots and displayed to be eligible for Price Setter status.
  • Orders will only lose Price-Setter status if another order sets a better price and is executed.

View our PSX Overview to see examples of the Price Setter Pro Rata model.

NASDAQ OMX Order Type Guide

NASDAQ OMX equity order types are designed to help members comply with regulation and execute a range of trading strategies. To better help members understand the available order types, we invite you to view our Order Type Guide.



The following protocols are available for accessing PSX:

To order ports, please email the completed PSX Port Request Form to For questions, contact NASDAQ OMX Subscriber Services at +1 212 231 5180.

Market Data

PSX TotalView-ITCH – Provides full order depth and last sale information.

PSX Historical TotalView ITCH – Offers a historical record of the order and trade transaction data from the PSX TotalView-ITCH data feed. Subscribers to this historical product may download daily transaction logs on a T+1 basis from a secured website or FTP server.

PSX Basic - Provides key data elements for all exchange-listed equities traded on the PSX execution system.

To subscribe to any of our market data products, please contact your NASDAQ OMX Global Data Products Account Manager at +1 301 978 5307 or visit the Global Data Products Administration page to complete the appropriate agreements and forms.



Please note: Although PSX plans to set all symbols to Price Setter Pro Rata on August 1, 2014, the proposed rule allows PSX to configure symbols as pro rata without the price setter incentive or as price/time. If PSX chooses to change the configuration of a symbol, ample notice will be given to members. The symbol execution algorithm settings can be found here.

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