Price optimization when the discounter cuts 1,200 lines

Lidl GB has put £400m into price cuts and promotions this year, across more than 1,200 products, and has set aside another £75m for its loyalty members between now and Christmas. In the US, Aldi says nearly a third of its everyday range is now cheaper than a year ago, with the latest round running until at least 3 November. Tesco, with 28% of the UK grocery market, gave back a little share and saw like-for-like growth slow to 1.3%. The discounters are spending. The leaders feel it. For everyone else this is a price optimization problem, not a price matching one.

If you run a regional grocer, a 200-store specialty chain or a mid-market online retailer, the email has probably already arrived from the board: what is our response? This memo is about how to answer it. The short version: do not answer with a list of 1,200 lines. Answer with price optimization on the 50 to 150 lines that set your price perception, funded by the thousands that do not, and governed by a rule you can explain.

Why matching 1,200 lines is the wrong answer

The reflex when a discounter cuts is to cut back. Line by line, category by category, until the gap is closed. It feels decisive. It is also the fastest way to turn a competitor's investment into your margin problem.

Three reasons. First, you do not have their volume. A discounter can fund a 10% cut on chicken with a tight range, private-label economics and supplier terms that come with scale. A mid-market retailer matching the same number on the same item books the cut in full and gets a fraction of the volume. Second, most of the 1,200 lines are not watched. Shoppers remember the price of a handful of items. They do not remember the price of the fourth variety of pasta. Matching the fourth variety costs money and buys nothing. Third, a blanket match has no funding mechanism. Every line goes down, nothing goes up, and the category P&L absorbs the whole bill.

The discounters know this. Aldi's latest US round is concentrated in fresh: chicken breast at $1.99 a pound, its lowest everyday price since 2022, and Honeycrisp apples at $1.99 a pound, down 35% on last year. Those are items shoppers price in their heads. Lidl's £400m went into staples, fruit, vegetables, meat and fish, the categories that anchor a basket. Neither is cutting everything. Both are cutting what people notice.

Price optimization starts with the lines that set perception

Shoppers are comparing more than they used to. In an Axonify survey of 1,200 grocery shoppers in the US and Canada, 88% said they shop at more than one store a month, and 69% of those do it to find better prices. 42% have cut visits to the store they used to go to most, and price was the main reason. The comparison is real. It is also narrow. Nobody is comparing 1,200 lines. They compare the twenty or thirty they buy every week and extrapolate to the rest of the store.

So the first job is to know which lines those are, for your shoppers, not in general. The usual label is KVI, key value item. The method is not complicated: rank items by purchase frequency, by penetration across baskets and by how often they appear in competitor promotions, then confirm with the elasticity you have actually observed when the price moved. In a 20,000-SKU assortment you will usually find 50 to 150 lines that carry most of the perception. We have written up the workflow in Closing the price perception gap and the definitions in What are KVIs in retail pricing.

Then compare on those. Not on the headline "we are 4% dearer than the discounter" the board read in a newspaper, but on a perception index: your price on the KVIs against theirs, weighted by how much each item matters. That is the number to move. The total-assortment index is the number to protect.

A price investment is a reallocation, not a cost

The second job is to fund it. The leaders do not book a price investment as a line of lost margin. They treat it as a reallocation from lines where price does not change behaviour to lines where it does.

The arithmetic is simple to describe and tedious to do by hand. Take the 150 lines you will invest in. Estimate the margin given up at the new price and the volume you expect back, using observed elasticity where you have it and a conservative category assumption where you do not. Then look at the long tail: the thousands of lines that shoppers do not price-check, that are rarely promoted, where you have been sitting below the market for no reason anyone can remember. A one or two percent move on a few thousand low-visibility lines, kept inside a margin floor and a market ceiling, is usually enough to pay for the head. Our category manager's playbook for portfolio price cuts walks through the bucket classification and the basket-level math.

Two guardrails. Do not fund the head from items that sit on the shopper's radar in another context, such as a seasonal line or a brand with a strong reference price. And do not fund it from your own private label if private label is your value message. That is where the discounters are strongest and where a visible gap costs the most.

Competition based pricing needs a rule, not a reflex

The third job is to write the rule down. Not "we will stay competitive". A rule a category manager can apply on a Tuesday and a CFO can audit in March. For example:

• KVIs (50 to 150 lines): within 2% of the lowest tracked competitor, checked daily, no exceptions without sign-off.
• Semi-KVIs (the next 300 to 500 lines): within 5% of the market median, checked weekly.
• Long tail: indexed to the market, never below a margin floor, never above a market ceiling, moved in small steps.
• Price matching promises, if you make them, apply to the first group only. "We match the discounter" across the range is a promise you cannot keep, and the shopper will test it on the line you forgot.

Competition based pricing written this way is explainable: anyone can see why a price moved, which competitor triggered it and which guardrail stopped it going further. It is auditable, which matters more every quarter as pricing regulation tightens. And it scales, because the rule does the work on 20,000 lines while your team spends its time on the 150 that matter.

Measure it weekly, on two indexes

A price investment that is not measured becomes a permanent cost. The board asked for a response; six months later it will ask what it bought. Set up the answer before you spend.

Two numbers, both weekly. The first is the perception index: your KVI basket against each tracked competitor, weighted by item importance. This is the one the investment should move, and you should see it move within a fortnight of the first price change. The second is the total-assortment index: every matched line, equally weighted. This is the one that should barely move. If it drops alongside the perception index, the funding step did not happen and you are simply cheaper.

Behind the two indexes sit three checks. Volume on the invested lines against the elasticity you assumed, so the forecast gets corrected rather than defended. Margin on the funding lines, so the tail is paying for the head and not just absorbing it. And basket size on the customers who buy the KVIs, because the point of winning the chicken is winning the rest of the trolley. Competitive pricing analysis at this level is a weekly habit, not a quarterly deck. The discounters re-price constantly; a quarterly read tells you what happened, not what to do.

Where retailers we talk to go wrong is not the analysis. It is the cadence. The data arrives weekly, the meeting is monthly, and the decision is quarterly. By then the discounter has moved twice.

What this doesn't change

A pricing rule is not a strategy. It will not close a structural cost gap. If a discounter's buying terms, range discipline and private-label share give it ten points of cost advantage on staples, no amount of price optimization makes you the cheapest on staples. It can make you close enough on the lines that matter that shoppers stop switching for them, which is a different and achievable goal.

It will not fix a weak private label. Lidl and Aldi win on own brand because the quality is credible and the range is tight. If your own label is an afterthought, a price match on it advertises the gap rather than closing it.

It will not substitute for the second investment the discounters are making. Lidl's £75m to Christmas is going into personalised coupons and member offers, not shelf prices. Lidl Plus transactions were up 17% in a month and coupon funding is up 60% this year. That is a price investment with a different mechanic, and it needs to be modelled as one. We covered how in Member pricing is a price cut: model it like one.

And it will not help if the response is late. Nearly half of US shoppers say they are worried about affording holiday gifts this year, and seven in ten say deals will decide where they shop. The discounters have timed their investment for exactly this window. A response that lands in February answers a question nobody is asking any more.

What to ask for this week

Three things, in this order. A list of the 50 to 150 lines that set your price perception, with the evidence for each. A funded proposal: what goes down, what goes up, and the net margin effect at a conservative elasticity. And the rule, written in plain language, with the guardrails and the weekly measures attached. If your team can produce those three in a fortnight, you have a response. If it takes a quarter, the tooling is the bottleneck, not the people.

Retailgrid is built for that fortnight: competitor prices in the same Grid as your costs and sales, rules written in plain English, and a weekly index your CFO can audit. If you want a quick outside view of where your price perception actually stands, our free pricing audit scans a store's pricing against the market and shows you the gap by product role. You can also read how competitive pricing works in the Grid, or talk to us about the specific discounter in your market.