Short answer
The market economy operator (MEO) principle asks whether a comparable private operator, pursuing an economic return under normal market conditions, could have entered the same transaction on the same terms. Its practical form changes with the transaction: an investment is tested against a private investor; a loan against a private lender, with risk reflected in interest, security and other terms; and a purchase against a private acquirer with a genuine commercial need.
The assessment is made ex ante, using information reasonably available when the authority committed itself. A public-policy objective does not by itself make the test inapplicable, but benefits and costs belonging only to the State's public role—such as regional development, jobs or exposure created by earlier unlawful aid—cannot be counted as an investor's return. A properly designed tender or meaningful private participation on genuinely equal terms can be strong market evidence. Without that evidence, the authority needs contemporaneous, objective analysis: credible forecasts, risk-adjusted returns, comparables and a realistic counterfactual.
Passing the MEO test means the transaction does not confer an economic advantage and therefore is not State aid on that basis. Failing it does not automatically make the measure unlawful: the remaining elements of Article 107(1) TFEU and any basis for compatibility still require separate analysis.
Why the question is about advantage, not public ownership
EU law is neutral about public and private ownership. A Member State may own shares, lend money or buy services. The issue is whether its counterparty receives terms it could not have obtained in an ordinary market transaction.
Article 107(1) TFEU supplies the controlling threshold:
“Save as otherwise provided in the Treaties, any aid granted by a Member State or through State resources in any form whatsoever which distorts or threatens to distort competition by favouring certain undertakings or the production of certain goods shall, in so far as it affects trade between Member States, be incompatible with the internal market.”
—
The MEO principle tests the “favouring” or advantage element. The comparison is functional, not formal. It concerns the economic substance of what the State did, even if it used legislation, a tax measure or an intermediary. The correct comparator must also resemble the public body's actual economic position: a long-term shareholder may behave differently from a short-term fund, while a secured lender behaves differently from an unsecured creditor.
What evidence is needed for a public investment?
For an equity injection or similar investment, the question is whether a rational private investor in a comparable position could have expected an adequate risk-adjusted return. Relevant tools include net present value, internal rate of return, the undertaking's financial position, sector and country risks, and credible alternative uses of the capital. A long investment horizon is possible, but it must still be guided by prospects of profitability.
Timing is decisive. In Commission v EDF, Case C-124/10 P, the Court of Justice required objective evidence that the investment decision existed when the advantage was granted:
“That evidence must show clearly that, before or at the same time as conferring the economic advantage, the Member State concerned took the decision to make an investment, by means of the measure actually implemented, in the public undertaking.”
—
A later consultancy report cannot reconstruct a commercial decision that was never made. Nor is actual success enough: a speculative investment does not become market-conform merely because it eventually made money. Contemporaneous board materials, forecasts, sensitivity testing, financing assumptions and alternative scenarios matter because they show how a prudent investor would have assessed the transaction at the time.
If public and private investors participate simultaneously, on the same risk and reward terms, economically significant private participation may provide direct evidence of market conformity. “Pari passu” is not a label: timing, terms, exposure and transaction costs must genuinely be comparable. A symbolic private stake, a side guarantee for the private participant or a materially different starting position weakens the inference.
How are public loans and debt measures tested?
For a new loan, the authority should price the borrower's probability of default, expected recovery, collateral, maturity, seniority, covenants and other transaction-specific risks. Comparable recent borrowing, bond yields or similar private loans are preferable evidence. Commission reference rates can be useful proxies, but they do not override better transaction-specific market evidence.
The Commission's 2016 Notice summarises the basic rule:
“In the same way as any other transaction, loans and guarantees granted by public bodies (including public undertakings) may entail State aid if they are not in line with market terms.”
—
Where the authority already holds a debt and grants extra time, writes down principal or restructures repayment, the practical comparator is usually a private creditor seeking recovery. In Frucona Košice v Commission, Case C-73/11 P, the Court required an overall assessment of what a normally prudent and diligent creditor would do, including the likely duration and recoveries under competing enforcement, arrangement and bankruptcy routes. The focus is therefore not simply whether the concession looks generous, but whether it is economically preferable to realistic alternatives.
Existing exposure needs careful classification. In Commission v FIH Holding and FIH Erhvervsbank, Case C-579/16 P, the Court held that risks arising from earlier State aid belong to the State's public role and cannot be used to justify a later measure as commercially rational. By contrast, a genuine pre-existing shareholding or market loan may be relevant if a comparable private operator could have held it. The counterfactual should compare the expected result of the proposed intervention with restructuring, enforcement, sale or liquidation, excluding costs that only a public authority would bear.
What changes when the authority purchases goods or services?
A contract and an invoice do not, by themselves, exclude State aid. The public acquirer must have a genuine economic need, buy an appropriate quantity and pay no more than normal market value on commercially rational terms. Requirements unrelated to the transaction's economic objective, purchases far beyond expected use, or payments intended chiefly to support the supplier can reveal an advantage even where a price benchmark looks plausible.
An open, impartial and non-discriminatory tender can establish a market price when it produces genuine competition and uses appropriate award criteria. But the Court of Justice made clear in Volotea and easyJet v Commission, Joined Cases C-331/20 P and C-343/20 P, that tendering is not the only method:
“However, it is also apparent from that case-law that the holding of such a procedure is not always mandatory for the purposes of such a sale or purchase transaction and, moreover, that there are other methods of ruling out the existence of such an advantage.”
—
Those alternatives include reliable independent valuation, comprehensive cost analysis and well-chosen comparables. The Court also placed the burden on the Commission to prove an advantage after a diligent and impartial investigation; it is not enough simply to note the absence of a tender.
Commission Decision (EU) 2024/3021 illustrates the purchaser issue. A German regional authority bought marketing services connected with an airport. The Commission examined the authority's own economic benefit, the absence of a contemporaneous business plan, its actual need for the services and whether regional-development aims were being treated as a commercial return. It concluded that the marketing payments were incompatible aid, while reaching different conclusions on other measures after examining their particular economics. The decision shows why each contract needs its own evidence; procurement compliance alone and a supplier's list price do not settle the State aid question.
A practical MEO review
Before committing public resources, record:
- the State's precise economic role: investor, lender, existing creditor or acquirer;
- the commercial objective, separated from employment, regional or sectoral policy aims;
- the information and forecasts available on the decision date;
- realistic alternatives, including no transaction, enforcement, sale or liquidation;
- the expected risk-adjusted return, total financing cost or value of the goods and services;
- transaction-specific comparables, a genuine tender or economically significant pari passu participation;
- differences in risk, security, seniority, timing, obligations and transaction costs; and
- who receives any direct or indirect advantage.
Keep the analysis contemporaneous and decision-ready. A file that states only a policy benefit, cites a later valuation or assumes that a public counterparty can accept a lower return is unlikely to answer the MEO question.
Conclusion
The MEO principle applies one economic idea through transaction-specific tests. Public investments need credible ex-ante prospects of a market return; loans need risk-adjusted terms and a realistic recovery analysis; purchases need a genuine commercial demand and market value. Strong direct evidence comes from genuinely equal private participation or a competitive tender, but robust valuation and benchmarking can also work. The central discipline is to compare like with like, using information available at the time and excluding advantages or costs that arise only because the actor is the State.
Sources
This article provides general legal information, not advice for a specific matter. Laws, facts and procedural deadlines may change the result. Follow the linked primary sources and obtain local advice before acting.