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Energy Markets GAS

HEnEx, a Nominated Electricity Market Operator (NEMO) for the Greek Bidding Zone, provides the market place, trading venues & platforms and delivers efficient price formation, for a secure and reliable energy trading in the South-East Europe. Our trading services are based on high European regulatory standards, ensuring transparency of transactions, low transaction cost and elimination of counterparty risk through the clearing and risk management of a Central Counterparty.

We operate the Energy Trading Spot System (ETSS) and Natural Gas Trading Platform powered by ATHEXGroup, offering web-based state-of-the art environments and Application Programming Interfaces (APIs) for customized individual trading management. ETSS supports all the standard PCR products and Order Types used in Single Day-Ahead Coupling and is further extended and integrated for accommodating local and regional intraday auctions trading. The Natural Gas Trading Platform supports short-term Standardized Products and provides a market to all interested Participants, gas suppliers, traders and final consumers. Τhe Hellenic Gas Transmission System Operator (DESFA) participates for the balancing needs of the National Natural Gas Transmission System.

Day-Ahead & Intraday Markets


In the context of the Integration of European Electricity Markets, HEnEx operates the Day-Ahead (DAM) and the Intraday Market (IDM) for electricity aligned to Target Model objectives.

DAM refers to buy and sell trades of electricity with an obligation of physical delivery for the next Delivery Day D, including the registration of energy quantities resulting from the trades carried out within HEnEx’s Energy Derivatives Market or from Over-the-Counter Energy Financial Instruments.

IDM refers to buy and sell trades of electricity with an obligation of physical delivery by submitting respective orders after DAM gate closure time, and includes three (3) Complementary Regional Intraday Auctions (CRIDAs).

Products & Order Types


Products admitted for trading on the Day-Ahead and Intraday Market, for each Market Time Unit, which is one (1) hour, of Delivery Day are types of commercial contracts of electricity with physical delivery (injection or offtake) within the Bidding Zones of the HTSO. The eligible order types as a result of the Products admitted for trading on the Day-Ahead Market, allowing for efficient sell and buy scheduling, are the following: 

   Hourly Hybrid Orders

   Block Orders

   Linked Block Orders

   Exclusive Group of Block Orders

The eligible order types as a result of the Products admitted for trading on the IntraDay Market are the following: 

   Hourly Hybrid Orders


Trading & Market Results


The Trading on HEnEx's Energy Markets is carried out electronically and anonymously through the Energy Trading System (ETS). The Day-Ahead Market Results consist of the Market Clearing Prices per Market Time Unit of the Physical Delivery Day and Bidding Zone, the Net Delivery Position of each Bidding Zone, and the acceptance status and ratio of Block Orders.

Natural Gas Trading Platform


The Natural Gas Trading Platform is an organized market operating in accordance with the Regulations EU BAL Network Code (Regulation (EU) 312/2014) and REMIT (Regulation (EU) 1227/2011), upgrading the operating framework of the existing wholesale gas market in Greece.

Participants in the Natural Gas Trading Platform can be the Transmission Users and DESFA. DESFA participates by trading in short-term Standardized Products for reasons of balancing the National Natural Gas Transmission System. The transactions that take place are anonymous while the quantities are automatically notified to DESFA.

Based on the transactions made in the Natural Gas Trading Platform, HEnEx calculates and publishes a set of Prices, including Closing Prices, the Next Day Gas Index (HGSIDA) and the Intraday Gas Index (HGSIWD) as well as Buy and Sell Marginal Prices.   


Products & Trading Methods


Available products include Title Products with delivery day one Gas Day at the Virtual Trading Point of the NNGS (Hellenic VTP). Trading is done daily, including holidays, for the following daily Contracts:  

   Intraday (current Gas Day D)

   Day-Ahead for the next three (3) Gas Days (Gas Days D+1, D+2 and D+3, respectively)

The trading means combine the following methods in the main trading board: 

   Automatic and continuous trading (continuous trading)

   Call Auction (auctions)

The main trading method is the continuous trading, which takes place from 08:30 CET to 18:00 CET. Additionally, auctions may be held at the request of DESFA for the balancing needs of the NNGTS, from 07:00 CET of the calendar day until 01:00 CET of the next calendar day, during the first 30 minutes of the respective hour following the announcement of the auction (eg 07: 00-07: 30, 09: 00-09: 30,…, 01: 00-01: 30). 

At the same time, the possibility of registration of pre-agreed trades (trade registration) in order to be cleared and settled by the Clearing House (EnExClear) is supported. The Trading System incorporates volatility control mechanisms and other additional functions for market protection purposes. 






Reference prices


HEnEx publishes a set of Reference Prices that serve as indicators for monitoring the current gas prices in the Greek HTP.

The following Reference Values are calculated:

Closing Prices

   Available daily at 01:45 CET

   Calculated as the volume-weighted average of last transactions covering 30% of the total volume for each Gas Day traded

   Four (4) Closing Prices are calculated daily, one for each Gas Day traded

HEnEx Gas Spot Index – Day Ahead (HGSIDA)

   Available daily at 18:15 CET

   Calculated as the volume-weighted average of transactions between 07: 00-18: 00 CET for the next Gas Day

HEnEx Gas Spot Index – Within Day (HGSIWD)

   Available daily at 18:15 CET

   Calculated as the volume-weighted average of transactions between 07: 00-18: 00 CET for the current Gas Day

Finally, HEnEx calculates and publishes the evolution of the Buy and Sell Marginal Prices for the Gas Balancing Market, in accordance with Regulation (EU) 312/2014 (EU BAL Network Code).

Trading _Contact

HEnEx Trading Support Dpt. 

E-mail : 
Tel : (+30) 210 33 66 845