A Varta battery went to the Moon.
- Neil Armstrong’s Hasselblad camera. Powered by a VARTA cell.
Before that, Varta batteries went with Roald Amundsen to the poles. The company started in 1887. Over 130 years of engineering nobody could question.
On 24 July 2026, Varta filed for insolvency.
Sit with that for a second. A company that survived the Moon didn’t survive one lost contract.
So what actually happened?
Varta had a plant in Nördlingen, Bavaria. It made the tiny rechargeable batteries inside Apple’s AirPods. Not one client among several. The client. That plant existed almost entirely for that one contract.
In May, Apple decided to move the work to a supplier in China.
The contract ends in October. Production stops in November. Around 350 jobs gone at that plant alone. More at risk across the wider group.
This isn’t even Varta’s first collapse. It was restructured in 2024, shareholders wiped out, creditors took a hit. This time the owners, Porsche and Michael Tojner, said no to more cash. The parent company and several divisions filed for insolvency.
Here’s the detail that matters most. One division was left out of the filing. The one that never depended on a single big customer. Household batteries. Worth around €240 million. Still standing.
Same company. Same 130 years of history. Same engineers. One division nearly gone, one division fine.
The quality was never the problem. It was never even in question.
So what was?
This is a conversation most founders avoid, because it doesn’t feel like a problem while it’s happening. It feels like the opposite. It feels like loyalty. Like a strong relationship. Like security.
It isn’t. It’s client concentration risk, and it’s quietly the most dangerous number in your business.
What Actually Killed Varta
Not the batteries. The dependency.
When one customer is nearly all of your output, you’ve stopped running an independent business. Your future now sits inside somebody else’s meeting. A meeting you’re not invited to.
And here’s the uncomfortable part: nobody did anything wrong.
Apple didn’t betray Varta. Apple has no obligation to keep a supplier alive. It answers to its shareholders, not to a workforce in Bavaria. A cheaper supplier that meets spec, that’s just procurement, doing its job.
The obligation sat on the other side.
It was Varta’s job to make sure no single customer could end it with one decision. And it failed at that. Twice. It had already had one near-death experience in 2024. Even that didn’t change anything structural.
The division that survived is the one that was never exposed like this.
That’s not luck. That’s the whole lesson.
This Isn’t a German Battery Story
It’s tempting to file this under “manufacturing problem.” Bavaria, component makers, big tech buyers with all the leverage. Not your world.
It is your world.
Look at any UK city with agencies, consultancies, engineering firms, professional services practices, you’ll find the same shape, different clothes.
How many creative agencies do most of their billable hours for one retained client?
How many engineering subcontractors live off a single automotive prime?
How many consultancies exist almost entirely inside one platform, one bank, one referral partner, a partner they’re contractually not even allowed to name?
And every single one of them will tell you it’s fine. “We’ve worked together for twenty years.”
Nördlingen worked with Apple for years too. Good components. Skilled people. Real trust, on both sides. A battery good enough for the Moon.
None of it saved the plant. Because none of it was ever what kept the plant alive.
What kept it alive was one commercial decision, renewed year after year, until the year it wasn’t.
How This Shows Up in Your Business
It rarely arrives as a single dramatic contract. It creeps in, dressed as success.
It looks like this: your biggest client keeps growing. They’re easy, they pay on time, so you keep saying yes to more scope. Two years later they’re 55% of revenue. You never decided that. It just happened, one good year at a time.
It looks like being the “safe pair of hands” a private equity portfolio keeps handing more work to, until one fund decision about approved suppliers ends it in a single quarter.
It looks like a firm getting nearly all its instructions from two referring accountants, who could just as easily start referring somebody else’s cousin next year.
None of these founders think of themselves as dependent. They think of themselves as trusted. Preferred. Embedded.
Varta’s engineers probably felt exactly the same way about Apple. Right up until May.
The Number You Need to Know
Do this now. Open your accounts. Work out what share of last year’s revenue came from your single biggest client.
There’s no official cut-off, but ask any M&A advisor and you’ll hear roughly the same thing. Above 20–30% from one client, questions start. Above 50%, it’s a standing item in due diligence and it shows up as a lower multiple, a nasty earn-out, or a buyer who quietly stops calling back.
You don’t need to be selling for that number to matter.
If one client is nearly half your revenue, that client sets your terms. Your margins. Your capacity planning. Probably your mood most Mondays.
That’s not a strong customer relationship. That’s a dependency with a logo on it.
Sit with your number for a minute before you carry on reading.
What I Learned From Being Told What I Was Worth
Early in my career, on a major infrastructure project, I wasn’t classified as an engineer.
Not because I couldn’t do the work. The structure I was in simply wouldn’t put me in that box. My competence was never the question. My status inside somebody else’s org chart was.
Then the engineering team ran out of budget on a specific calculation, a windpost, load-bearing, non-negotiable. Suddenly I was exactly who they needed.
My value hadn’t moved. Their constraint had.
That’s the part I never forgot. For a long time, someone else’s convenience decided whether I was “in” or “out”, not my competence.
Varta’s engineers could design a coin cell that survives a decade of daily charging. That expertise was never what decided whether Apple stayed. Apple’s constraints changed (cost, geography, supply chain) and the decision followed the constraint, not the quality.
well-run department inside somebody else’s.
The Three Faces of Founder Dependency and Why This One Moves Fastest
Founder dependency in a service business usually shows up three ways: client dependency, knowledge dependency, sales dependency.
Knowledge dependency erodes you slowly. Know-how stuck in one head makes you inefficient and hard to scale but it rarely ends the business overnight.
Sales dependency starves you over months. If new business runs entirely through the founder’s network, the pipeline dries up gradually when they step back.
Client concentration risk is different. It’s binary. It’s immediate.
One procurement decision. One merger on the client’s side. One new CFO who wants to consolidate suppliers. And the revenue is gone before your next invoice.
Nördlingen didn’t decline slowly. It had a decision in May and a closed plant by autumn.
That speed is exactly why founders underprice this risk. Knowledge gaps and slow sales feel urgent, because you fight them every day. A dominant client relationship feels like the opposite of a problem, right up until it’s the only problem left.
What Buyers, Investors and Your Own Clients Quietly See
Clients buy delivery. Buyers buy a business. Nothing exposes that gap faster than customer concentration.
When an acquirer, an investor, even a bank looks at your numbers, they’re not just asking if you’re profitable. They’re asking what happens to that profit the day your top client leaves.
If the honest answer is “we’d be in real trouble,” that shows up immediately. Lower multiple. A brutal earn-out tied to retention. Or a deal that quietly stops returning your calls.
Here’s the part founders find harder to hear: your other clients are running the same maths, even if they never say it out loud.
the others walks. A senior client who knows they’re 60% of your revenue starts wondering something worse, will you ever push back on scope or price, when saying no to them puts your whole business at risk?
Risk-aware clients don’t want a single point of failure in their own supply chain. A firm that’s dependent on one other customer is exactly that, dressed up as a trusted partner.
The relationship is the real product. Trust is the leverage. But trust concentrated in one relationship isn’t strength. It’s the whole business balanced on one point.
Why Being Good at the Work Isn’t Enough
Ask a founder why they don’t worry about this, and most say some version of the same thing: “our work speaks for itself.”
Speaks to whom?
If the honest answer is “to the one client who already knows us” — that’s not a market position. That’s a private conversation happening inside somebody else’s supplier list. Excellent. Well regarded. Completely invisible to everyone who might need you next.
Good delivery earns you the next invoice from the client you already have. It does almost nothing to earn you the next client you don’t have yet.
Those are two different jobs. Most founder-led firms have only ever staffed one of them, because delivery is loud and urgent, and being known beyond your biggest account is neither.
A firm that’s done both jobs can lose its biggest client and still be standing a year later. A firm that’s only ever done one is, functionally, a very well-run department inside somebody else’s business — worth exactly as much as its next purchase order, however good the work is.
This isn’t a marketing exercise. It’s a structural one. ever been allowed to become existential. Instead, nothing structural changed. Eighteen months later, the same dependency finished the job.
That’s how this compounds. Every year a dominant client relationship goes unchecked, three things happen at once. Your negotiating position weakens, because they know exactly how much you need them. Your muscle for winning new business atrophies, because you haven’t had to use it. And the eventual work of diversifying gets harder, because you’re now starting from visible weakness instead of strength.
None of this requires you to be planning a sale. A business that’s dangerously reliant on one client is more fragile today — worse cash flow risk, worse negotiating position, worse sleep — whether or not you ever intend to exit.
Diversifying your client base isn’t exit prep. It’s what a resilient, well-run company looks like on an ordinary Tuesday.
Knowing this isn’t enough. Only action changes anything. And the action starts with the number you worked out a few sections ago.
Ready to Find Out Where You Stand?
If you recognised your own numbers somewhere in Varta’s story, the next step isn’t a dramatic client cull. It’s clarity.
A Founder Dependency Audit or Value Gap Review looks honestly at your business across five areas, including client concentration, and tells you (in plain terms) where the real risk sits and what to do about it first.
The output is a written report and a 90-minute debrief. Specific to your business, not a generic framework.
Book a free discovery call to find out whether a diagnostic makes sense for you.
