What is the EU 30-day rule for price reductions? Under Article 6a of the Price Indications Directive, any announcement of a price reduction must state the prior price, defined as the lowest price the trader applied during a period of not less than 30 days before the reduction. Raise the price for a week, cut it back, and advertise the cut as a discount: that is precisely the practice the rule was written to end. It has applied across the EU since 28 May 2022, and it sits directly underneath one of the most attractive numbers in an e-commerce CIM: an above-market conversion rate.
The GP3 Waterfall treats GM3 as the marketing-efficiency layer: what it costs to turn ad spend into orders. A strike-through price is not a marketing cost, so it never appears in that layer. But it does the same work an ad does. It moves a visitor from considering to buying. A target whose catalogue is permanently “40% off” against a reference price nobody ever paid is running a second, invisible conversion engine, and the P&L books that engine’s output as the performance of the paid one.
The Mechanism
Reference-price anchoring is one of the most reliable effects in pricing. The same €59 product converts differently when displayed as “€99 was €59” than as a plain €59, even when €99 was never seriously charged. The anchor does three things at once: it lifts conversion rate, it supports a higher actual selling price than the product would carry unanchored, and it manufactures urgency that shortens the consideration window.
The operational patterns that follow are familiar from any sustained look at e-commerce pricing:
- The permanent sale. A sitewide or category-wide “sale” that has no observable beginning or end. The discounted price is simply the price; the reference price exists only as an anchor.
- The pre-promotion markup. Prices raised in the weeks before a major promotion window, then cut back to roughly their ordinary level and advertised as deep reductions. This is the specific cycle the 30-day rule targets.
- The inflated RRP. A “recommended retail price” set far above any price the market actually clears at, used as the standing reference for a permanent discount percentage. This variant sits in murkier legal territory than the other two, covered below.
None of this requires touching the product, the ad account, or the checkout. It only requires deciding what number to print next to the real one.
Where This Sits in EU Law: Article 6a of the Price Indications Directive
The Omnibus Directive (EU) 2019/2161 inserted Article 6a into the Price Indications Directive 98/6/EC, with effect across the EU from 28 May 2022. The core rule is short: any announcement of a price reduction must indicate the prior price, and the prior price is the lowest price the trader applied during a period not shorter than 30 days before the reduction.
The European Commission’s guidance on Article 6a (2021/C 526/02) makes the scope wider than many traders assume: the rule is not limited to explicit percentages. Banners like “sale,” “special offers,” or “Black Friday deals” that create the impression of a price reduction fall within it too. Member states may provide narrow carve-outs (goods liable to deteriorate rapidly, goods on the market less than 30 days, and progressive reductions within one campaign), and national implementations differ in detail, which is a point for counsel to check per market rather than something this piece can settle generally.
One boundary worth flagging for counsel rather than settling here: a comparison against an RRP, presented as a comparison with another reference rather than as a reduction of the trader’s own prior price, may sit outside Article 6a’s literal scope. It is then assessed under the general misleading-practice rules of the Unfair Commercial Practices Directive instead, where the question becomes whether the RRP is genuine. Where that line falls varies by market and presentation, and it is a per-target legal question, not something outside-in analysis can conclude on its own.
Two enforcement layers sit on top. The Price Indications Directive itself is enforced nationally, with penalties set by each member state. An artificial reference price can also amount to a misleading commercial practice under the UCPD, an assessment national authorities and courts make case by case, and for widespread infringements of the UCPD as amended by Omnibus, member states must provide for fines whose maximum is at least 4% of the trader’s annual turnover in the member states concerned. Whether a given target’s practice meets the legal threshold of a widespread infringement is again a question for enforcement authorities and counsel; the diligence point is only that a pricing pattern replicated across product pages in multiple markets is the kind of pattern that regime was built for.
This is not theoretical enforcement. In a sweep published in March 2026, the Commission and consumer authorities from 23 member states plus Iceland and Norway checked 314 online traders’ Black Friday discounts and found roughly 30% referencing discounts incorrectly. National authorities have been running these sweeps, and following up on them, since the rule took effect.
Aldi Süd Closed the Percentage Loophole
For the first two years, some traders read Article 6a narrowly: display the 30-day lowest price somewhere on the page, but keep calculating the advertised percentage against the most recent (higher) price. The Court of Justice ended that reading in Case C-330/23 Aldi Süd (26 September 2024): a price reduction announced as a percentage, or presented as a price highlight, must be determined on the basis of the 30-day lowest price itself. Printing the prior price in small type while the headline percentage is computed against an inflated base does not comply.
The judgment matters for diligence because it narrows a gray zone considerably. A target computing ”% off” against the most recent higher price is running a practice the Court has specifically rejected in the scenario it ruled on; how far the reasoning extends to adjacent presentations is for counsel to assess against the judgment itself. Either way, the direction is unambiguous, and the practical takeaway for a buyer is the same: the base of the percentage is now a checkable compliance question, not a stylistic choice.
The Fake GM3 Problem
Now put the two halves together. The anchor lifts conversion and supports the selling price. In the P&L, that lift is invisible as a cause and very visible as an effect: ROAS looks strong, CAC looks low, the conversion rate benchmarks above the category. Every one of those numbers is partly the anchor’s output, misattributed to the ad engine, the creative, or the brand. The result is a GM3 that reads as marketing skill while resting, in part, on a pricing practice that may not survive regulatory scrutiny.
What makes this a repricing issue rather than a footnote is what happens if the practice has to normalise, and post-close there are three separate routes by which it can: the acquirer’s counsel requires it, a national authority orders it, or a sweep catches it. Compliant reference pricing under Article 6a and Aldi Süd means the displayed anchor becomes the lowest price of the prior 30 days. For a catalogue on permanent promotion, that collapses the displayed discount toward zero: the “40% off” becomes “€59, was €59.” The anchor stops working. Conversion reverts toward what the product earns unanchored, CAC rises to buy back the lost volume, and GM3 compresses, exactly the degradation-under-scale pattern the GP3 Waterfall flags as diagnostic. The mechanism differs from brand-retailer auction conflict, but the diligence failure is the same: a blended GM3 that cannot show which engine is producing the orders.
There is a revenue-quality layer beneath the margin layer. If the discount is permanent, the discounted price is the real price, which means the target’s gross-to-net bridge is describing a discount lever it does not actually have. An acquirer modelling promo depth as a tunable post-close lever is modelling headroom that was spent before they arrived.
Why This Slips Through Due Diligence
The data room shows a promotion calendar, and a promotion calendar looks like strategy. QoE tests whether the margins reconcile, not whether the reference prices behind the conversion rate were lawful. Legal diligence reviews contracts, policies, and terms, not the price history of the live site. And the practice itself is only visible longitudinally: a screenshot of a product page on any given day shows a compliant-looking strike-through. It is the same page observed across 60 days that shows the anchor never moves, or moves up just before it is “cut.” A data room is a snapshot by construction. This finding lives in the time dimension the data room does not have.
What Outside-In Analysis Can Detect Before the Data Room
- Price-history tracking of the target’s catalogue: whether displayed reference prices correspond to prices actually charged in the prior 30 days, and whether “discounted” prices are simply the standing prices, observable via archived snapshots and longitudinal monitoring of live product pages
- The base of the percentage: whether ”% off” claims are computed against the 30-day lowest price (the Aldi Süd requirement) or against a recent higher price or RRP
- Whether a prior price is displayed at all next to reductions, and whether sale banners and countdown timers cycle or reset without the underlying prices changing
- Advertised discount claims in ads, newsletters, and affiliate feeds compared against the observed everyday price of the same SKUs
- The share of the catalogue on permanent promotion: a “sale” covering most of the range for most of the observation window is a structural finding, not a campaign
- Reviews and forum mentions filtered for pricing patterns (“always on sale,” “never pay full price,” “price went up before Black Friday”)
The Pre-LOI Question Every PE Fund Should Ask
Not “what is the conversion rate”: an above-market conversion rate can be earned by product and brand, or manufactured by an anchor, and the number alone doesn’t say which. The question is: how much of the target’s conversion is doing the anchor’s work, and would GM3 hold if every displayed reference price were, as Article 6a requires, the lowest price of the prior 30 days?
A target that converts on compliant pricing owns its GM3. A target that converts on inflated reference prices is borrowing its GM3 from a practice of the kind the Court has ruled against, with an active enforcement regime behind it, and the question of whether that GM3 survives compliant pricing lands on the acquirer’s desk no later than close.
This analysis is part of Tronvik’s GP3 Waterfall methodology, focused on GM3 marketing-efficiency mapping. Nothing in this article constitutes legal advice. To initiate an outside-in pricing-compliance screen on a specific acquisition target, contact info@tronvik.com.