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LME Gateway Documentation

Understanding the Price Feed

Market Data Terms

The following table lists terminology that is specific to LME:




A market condition in which a price is lower in the distant delivery months than in the near delivery months.


Backwardation is associated with Carries.

Carry (Spread)

The simultaneous purchase and sale of the same tonnage of the same metal for delivery on different dates.


A market condition in which a price is higher in the distant delivery months than in the near delivery months.


Contango is associated with Carries.


Due for immediate delivery.

Prompt Date

The delivery date of a futures contract.


On LME, “ring” may have two meanings:

  • The circle of seats on the LME floor that brokers occupy when trading.
  • The periods of trading that are broken down into five minute sessions for each metal. This is the more common usage.

LME uses the following contract naming conventions:



3D Wednesday (3rd Wednesday)

A monthly prompt date on every third Wednesday.


3rd Wednesday contracts appear in Market Explorer with the following convention: Month, Year (e.g., June09)


A monthly prompt date.


A prompt date that is two business days forward.


A prompt date that is the next business day.


A trade that is carried out after the normal period for a cash trade. This trade must be done before the start of the official rings at 12:30 (GMT) and must be for delivery on the next business day.

Price Server Data Flow

The following is a description of the Price Feed connection from the Price Server on the TT LME Gateway to the TT LME Gateway host.

  • The Price Server starts and creates a new Price Server log.
  • The Price Server reads the hostinfo.cfg file to determine the Host connection information and its behavior when logging to the TT LME Gateway log files.
  • The Price Server logs into the TT LME Gateway host using the information from the hostinfo.cfg file. It writes this login information to the Price Server log.
  • Using X_TRADER®, a trader logs into the TT LME Gateway.
  • The trader opens the Market Explorer and requests products.
  • The trader opens Market Grid or MDTrader and subscribes to price updates.This information is passed to the Price Server, which then subscribes to the inside-market data for these particular products.

    Inside-market data consists of a set of contract attributes and includes Best Bid, Best Ask, Last Traded Price, etc.

  • The TT LME Gateway Host sends only the price and product information to which the Price Server subscribed.
  • Using a unique multicast group, the Price Server broadcasts the inside-market data received from the TT LME Gateway host.

    When a trader opens MD Trader™, the Price Server also subscribes to market depth.

  • The Price Server continues to multicast product and price information for which there are X_TRADER® subscribers.

    The Order Server will start after the Price Server has downloaded at least one product and becomes Active.