Tesco, Sainsbury's, and Asda are tired of playing by a set of rules that don't seem to apply to the German upstarts currently eating their lunch. For years, the UK's biggest supermarkets have operated under the watchful eye of the Competition and Markets Authority (CMA), specifically bound by a 2010 order designed to stop them from land-grabbing and blocking rivals. But here’s the kicker: Aldi and Lidl were never part of that deal.
Back then, they were viewed as "limited assortment discounters"—small-scale players that didn't pose a real threat to the weekly shop. Fast forward to 2026, and that label feels like a joke. With Aldi and Lidl now commanding nearly 19% of the market and operating thousands of stores, the "Big Four" are demanding the CMA level the playing field. They want the watchdog to treat the discounters like the retail giants they've become.
The land grab loophole that changed British high streets
If you've ever wondered why an Aldi or Lidl seems to pop up on every corner while your local Tesco struggles to expand, you've found the heart of the grievance. Under the Groceries Market Investigation (Controlled Land) Order 2010, designated large retailers are banned from using restrictive covenants. These are legal clauses that prevent a piece of land from being used by a competitor.
Tesco or Sainsbury’s can’t buy a plot of land and say, "No other supermarket can build here for 20 years." But because Aldi and Lidl weren't "designated" under that 2010 order, they haven't faced the same scrutiny. Retail executives argue the discounters have been using these exact tactics to lock out competition in growing neighborhoods. It's a classic case of regulation failing to keep up with reality.
The CMA has finally opened an "Invitation to Comment" as of March 2026 to decide if it's time to officially designate Aldi and Lidl as Large Grocery Retailers. If that happens, the wild west of discount land acquisition is over.
Why the limited assortment label is dead
The primary defense for the discounters has always been their "limited" nature. The logic went that if you can't buy a lawnmower, a specialized brand of organic cat food, and a specific brand of high-end gin all in one place, it isn't a "full-service" supermarket.
That distinction has evaporated. Look at the aisles today.
- Aldi now stocks everything from premium Wagyu steaks to middle-aisle power tools.
- Lidl has expanded its fresh bakery and wine cellar offerings to rival Waitrose.
- Both have integrated sophisticated wholesale and supply chain operations that mirror the Big Four.
The traditional giants argue that the "Limited Assortment Discounter" (LAD) tag is a relic of the past. When Aldi holds over 10% of the market and generates nearly £18 billion in turnover, it isn't a niche player anymore. It’s a predator.
The price of an uneven playing field
This isn't just corporate whining about lost profits. It affects what you pay at the till. When one or two players can use land agreements to keep rivals away, local monopolies form. If a discounter can block a mainstream supermarket from opening nearby, they don't have to worry about the mainstream player's aggressive price-matching schemes or loyalty card discounts.
The Big Four have been forced to invest billions into "Aldi Price Match" campaigns to stop the exodus of shoppers. They're doing this while also complying with the Groceries Supply Code of Practice (GSCOP) and the 2010 Land Order. They basically feel like they're running a race with weights on their ankles while the discounters sprint ahead in carbon-fiber shoes.
What happens if the CMA actually acts
If the CMA decides to designate Aldi and Lidl as Large Grocery Retailers, don't expect them to stop growing. Instead, expect their growth to become more transparent and "fairer" in the eyes of the law.
- Restrictive Covenants will vanish: They won't be able to stop a Tesco Express or a Sainsbury’s Local from opening next door to a new Lidl.
- Increased Reporting: They'll face the same rigorous reporting standards as the Big Four, making their land deals public knowledge.
- Operational Friction: Compliance costs money. The discounters have stayed lean partly by avoiding the bureaucratic overhead that comes with heavy regulation.
The CMA’s CEO, Sarah Cardell, has signaled that the watchdog is focusing on "proportionality" and "pace" in 2026. They know the cost-of-living crisis made Aldi and Lidl the heroes of the British household, but they also know that a market where two players get a free pass on competition rules isn't a healthy market for the long term.
Your move as a consumer
While the lawyers and regulators argue over land rights and market definitions, the reality for you is simpler. The "Big Four" aren't going to win this battle just by complaining to the CMA. They’re going to win by making their stores more attractive than the discounters.
If you're a shopper, watch your local planning applications. If you see a new supermarket development blocked, it might just be the result of the very land-use tactics the CMA is currently investigating. For now, take advantage of the fierce price wars. Whether or not the discounters get "reined in," the pressure on the Big Four to keep prices low isn't going away anytime soon.
Pay attention to the "unit pricing" on the shelves. The CMA is already cracking down on retailers who hide the true cost of items behind confusing labels. Compare the price per 100g, not just the big number on the front. That’s where the real savings are found, regardless of who owns the land under the store.
