ACER notifies the National Regulatory Authorities (NRAs) of suspicious behaviour in two main ways:
by sharing the screened alerts on a monthly basis; and
by sharing an Initial Assessment report, which includes details about the suspicious behaviour by one or more market participants.
The first figure provides a rounded monthly average of the alerts triggered (in thousands) manually assessed (in hundreds), and shared with the NRAs for the years 2017 - 2024.
Note: the monthly average is calculated taking into account only the months for which alerts were shared with the NRAs.
The second figure provides an overview of the number of Initial Assessment reports shared with NRAs (in total per year since 2015).
The map provides an overview of the number of alerts shared per country for the year 2023.
Looking at the total records reported to ACER since the beginning of data reporting, the alerts statistics indicate the amount of resources required in order to assess the REMIT data.
After screening the alerts, ACER performs an in-depth analysis of the observed suspicious behaviour by using a series of sophisticated tools. These tools allow the analysts to get specific statistics per market participant, for instance their trading behaviour per delivery point or zone, as well as cross-border trading.
The video shows a mock-up of trading behaviour per country.
The video illustrates one of the surveillance tools used in order to work with the REMIT data and, subsequently, assess the behaviour of respective market participants.
ACER uses a holistic approach to detect potential suspicious behaviour.
The different kinds of suspicious behaviour presented in ACER's Guidance Notes are translated into logic that creates bespoke alerts.
A surveillance tool, tailor-made for EU wholesale energy markets, is used to construct, trigger, prioritise and screen the alerts.
The detection of suspicious behaviour happens on two levels:
the first level of detection already happens when the alerts are triggered, as they automatically screen the REMIT data and trigger when they detect instances of behaviour that meet the alert logic and parameters.
The second level happens when the surveillance analysts screen the triggered alerts and assess the gravity of the suspicious behaviour.
ACER aims to revise the alert logic and parameters on a regular basis to enhance their effectiveness and efficiency, and to make sure they are adjusted to the latest market developments.
ACER always keeps an eye out for potential data quality issues and acts appropriately to resolve them.
ACER, an EU Agency, is entrusted with oversight of trading on Europe’s wholesale energy markets. In 2025, 19.9 bn transactions data was reported to ACER.
Data quality, transparency and confidentiality are cornerstones of our work. We adhere to international standards on how we collect, protect and publish data.
ACER provides evidence of the data quality assessments either by publishing dedicated open letters or via its REMIT quarterlies.
ACER strives to ensure that all collected data is complete, accurate and submitted in a timely way. Our data quality checks follow a two-step approach:
1. Data validation
When data is submitted in a data record by reporting entities to ACER's REMIT Information System (ARIS), automatic validation occurs at two levels:
technical validation: making sure all data fields in the data record are complete and in the correct format; and
database validation: ensuring reported data is consistent with reference data.
Any invalid or inconsistent data record is rejected and flagged, ensuring that only information succeeding the preliminary screening is stored in ACER's REMIT database.
2. Quality assessment
After data is collected, ACER's analysts conduct additional quality checks to confirm that it is accurate, complete and reliable, and follow up on any detected issues.
Dimension
Description
Example
Completeness
All required data fields for the specific data type are reported.
How much required data has been submitted.
Uniqueness
No data record is reported twice.
Duplicate trades are flagged if reported twice.
Timeliness
Data is reported correctly after the actual event.
The time difference between when the event occurred and when it was reported is consistent with the timing set in the REMIT Implementing Regulation.
Validity
Data follows correct format and rules.
Fields are filled in correctly and match expected structure.
Accuracy
Data accurately reflects the business event.
Reported prices, volumes, units, timestamps and identifiers match the real trade.
Consistency
Data matches across all reporting platforms.
Same trade reported on different platforms shows the same information.
Why you can trust ACER, the EU Agency whose work builds trust in energy markets
This section outlines why we in ACER collect energy data (our legal mandate), what energy data we collect, how we do it (data reporting) and how we ensure high data quality (through rigorous checking procedures) and confidentiality.
Two key features distinguish ACER from other energy data sources:
our legal standing as an EU Agency; and
our mandate in monitoring and assessing trading activities and in building trust in the integrity of EU energy markets.
REMIT is the EU-wide framework that protects wholesale energy markets from abuse, ensuring open and fair competition. Under the REMIT Regulation, ACER is mandated to collect data to monitor and assess trading activities on wholesale energy markets across the EU.
This EU-wide oversight of every trade in energy wholesale markets is unique to ACER.Working closely with national regulatory authorities (NRAs), we detect potential market abuse (such as insider trading and market manipulation). This supports market integrity, transparency and fair price formation.
Beyond its REMIT mandate, ACER also collects other data on wholesale and retail energy markets (e.g. under the electricity Capacity Allocation and Congestion Management (CACM) Regulation) to support its broader monitoring.
ACER and national regulatory authorities (NRAs) work closely together to protect energy markets from abuse. Increased transparency and monitoring build confidence that energy markets work well for EU businesses and citizens and that prices are determined in a fair way.
Data collection
What has changed in terms of data collection under the recast 2026 REMIT Implementing Regulation?
The rules for reporting energy market data to ACER are set out in the REMIT Implementing Regulation. Following the 2024 revision of REMIT, the Implementing Regulation has been updated in 2026 to include:
new quarterly ‘exposure’ reporting, which requires market participants to report their trading positions (i.e. showing how exposed they are to future energy price movements over the next 18 months);
new reporting elements for algorithmic trading and Direct Electronic Access (DEA);
a clarified definition of obligations for ‘organised market places’ (OMPs) and other reporting parties;
extended reporting obligations for Liquified Natural Gas (LNG) and hydrogen transactions; and
the introduction of ‘periodic data reporting’ (e.g. for balancing processes).
Based on these rules, ACER sets the procedures, standards and electronic formats (including reporting manuals such as the Transaction Reporting User Manual) that market participants must follow when submitting data. This centralised and structured system supports consistent data collection and effective market monitoring.
A full list of relevant documents is available on the REMIT Documents page.
Data collection
What energy data is collected?
Image
To fulfil its mandate, ACER collects several types of data, including:
Transaction data: Records of trades and orders to trade relating to wholesale energy products, either traded on 'organised market places' (OMPs) or bilaterally. The wholesale energy product definition encompasses supply, transportation capacity allocation and storage of electricity, natural gas and hydrogen. This includes information on product type, quantity, price, delivery date, counterparty and beneficiary.
Inside information: Market-sensitive information that must be publicly disclosed under REMIT, so that all market participants receive it transparently and at the same time. This concerns events that may affect wholesale energy prices (such as planned outages, unavailability, reduced capacity, maintenance delays or other events affecting production, storage or transmission).
Fundamental data: Information about energy assets, such as capacity and use of facilities for the production and storage of electricity, gas, LNG and hydrogen, including storage levels, consumption, transmission and generation outputs, as well as planned or unplanned outages.
ACER may request additional information or clarifications from market participants and reporting parties if the data submitted is incomplete or unclear. Reporting parties are responsible for submitting complete, accurate and timely data in line with the legal requirements and reporting arrangements.
ACER is committed to establishing and maintaining a strong working relationship with European academics and researchers.
Collaboration with academia is necessary in preparing ACER for future challenges and opportunities created by advances in science and technology.
A forward-looking engagement
Academics and researchers can participate in the work of ACER in several ways:
as members and experts of ACER's ad hoc expert groups;
as seconded national experts;
as short-term visiting experts;
by contributing to ACER's public consultations;
by taking part in ACER's conferences and workshops; and
by proposing REMIT data research projects for scientific purposes, subject to confidentiality requirements.
ACER is working to make non-sensitive data available for scientific purposes to further expand its collaboration with academia and contribute to effective knowledge sharing.
ACER can set up Expert Groups to provide ad hoc support and advice on REMIT topics.
In appointing the Expert Groups' members, ACER seeks to ensure a balanced representation of market participants, organised markets and other persons professionally arranging transactions, users and distributors of wholesale energy market information (e.g. information providers, analysts), and ENTSOs.
Since the entry into force of the European Commission's Implementing Regulation, market participants and third parties acting on behalf of market participants are obliged to provide ACER with a record of their wholesale energy market transactions, including orders to trade.
ACER registers market participants and third parties reporting on their behalf as registered reporting mechanisms (RRMs) to ensure efficient, effective and safe exchange and handling of information.
To discuss the views and practices of the reporting parties on REMIT data collection, ACER regularly organises Roundtable meetings in Ljubljana. These meetings are attended by:
Inside information platforms (IIPs): IIPs enable market participants to share inside information with the wider public, in accordance with the minimum quality requirements listed in the ACER Guidance.
Organised market places (OMPs): OMPs include electricity and gas exchanges, brokers and other persons professionally arranging transactions, and trading venues.
Registered reporting mechanisms (RRMs): RRMs represent all registered reporting entities, and include market participants, OMPs, ENTSOs, and third party reporting on behalf of entities under the data reporting obligation.
Webinars
To dynamically address any operational topics and ad hoc issues the reporting parties may be facing, ACER also holds periodic webinars with RRMs and OMPs.
These webinars are organised on ad-hoc basis, and the attendees can propose discussion topics via dedicated forms.
Public consultations
ACER regularly launches public consultations to invite all interested parties to provide their views on specific data collection issues.
National regulatory authorities (NRAs) have a key role to play in ensuring that each European country meets its targets for energy markets and implements the relevant EU regulatory policy.
In order to maintain the proper functioning of the single European market in gas and electricity, ACER supports NRAs in performing their regulatory function at European level and coordinates their contributions.
The key role of NRAs
Documents
ACER Working Groups are established based on a Director's Decision and can advise on the Agency's regulatory activities. They are composed of representatives from ACER, from NRAs, and from the European Commission.
To facilitate knowledge sharing and support the NRAs in the implementation of REMIT, ACER has established dedicated working groups, committees and task forces:
The ACER REMIT Committee (ARC) convenes on a quarterly basis.
There are currently two REMIT task forces reporting to the ARC. Task forces (TF) are informal, ad hoc groups, set up by the ACER Working Groups Chairs to provide expert support on specific topics.
Focuses on the analysis of REMIT data collected via the data reporting process and the improvement of data quality. The MD SC convenes on a quarterly basis.
Market Coupling Project Team (MC PT)
Focuses on the efficient integration of market coupling data in the data reporting process. The MC PT convenes virtually on a biweekly basis.
Provides a forum to debate the application of REMIT to specific market abuse cases, on the surveillance of wholesale energy markets and the coordination on REMIT cases. Convenes approx. 5 times per year.
REMIT Information Security Implementation Group (RISIG)
Provides support, advice and coordination on the definition and implementation of ACER's REMIT information security policy. Convenes on a quarterly basis and carries out, upon request, ad hoc peer reviews of NRAs' compliance with the policy.
ARIS NRA User Group (ANUG)
Provides support to the end users of ACER's REMIT Information System (ARIS). Convenes virtually on a bimonthly basis.
Inside information platforms (IIPs): Platforms that enable market participants to share inside information with the wider public (in accordance with minimum quality requirements listed in ACER's Guidance).
Organised market places (OMPs): Electricity and gas exchanges, brokers, persons professionally arranging transactions and trading venues.
Registered reporting mechanisms (RRMs): All registered reporting entities, including market participants, OMPs, European Networks of Transmission System Operators (ENTSOs) and third parties reporting data on behalf of other entities.
ACER engages widely on REMIT implementation (e.g. on the revision of related guidance), including through:
public workshops, webinars and events (e.g. annual REMIT workshop);
roundtable meetings with data reporting parties;
public and targeted consultations;
bilateral exchanges (e.g. through the Market Surveillance Forum (MSF) and the Energy Trading Enforcement Forum (ETEF)); and
Memorandums of Understanding (MoUs) (e.g. with NRAs, ESMA, OMPs and the US Federal Energy Regulatory Commission (FERC)).
While the MoU with the NRAs is a multilateral one, MoUs with OMPs are bilateral. This allows OMPs to set out the content and procedures for the cooperation on more specific issues related to market monitoring under REMIT. ACER had signed MoUs with eight organised market places across the European Union.
. 
