Altnet Economics Explained: Why the Fibre Boom Is Consolidating
Britain built more fibre networks than it can pay for, and the reason is not mysterious. A fibre network costs everything before it earns anything, it only earns from the homes that sign up, and most of the money that built the independent networks was borrowed when interest rates were near zero and is being serviced now that they are not. Our consolidation report forecasts how that ends. This page explains the arithmetic underneath, in plain terms, and then turns it round to the only question that matters to a household on one of these networks: what should you check?
The short version
- The dig costs the same whether 18 homes or 40 sign up. Take-up is the only lever. Altnets average 18%; Openreach is at 40%.
- The money was borrowed at near-zero rates and is serviced at real ones. 47% of UK fibre companies face refinancing by 2026.
- The largest altnets lost £1.5 billion in 2024. Most cover their running costs; few cover their debt.
- Funding is back, but only for proven take-up. £0.6 billion in 2024, £3.2 billion in 2025, mostly to CityFibre.
- Your fibre keeps working through all of it. What changes is the name on the bill and sometimes the price. Check your contract's price terms now.
Reading this for something else? The forecast, the odds, the four exits and the overlap map are in The Great Consolidation, Report No. 27, which this page does not repeat. How the wholesale layers fit together, and what an anchor tenant is, are in our wholesale explainer. The largest live case is the CMA's nexfibre decision. What happens to your contract when a provider changes hands is here, and who holds how much of the market is in our market share report. This page is the arithmetic.
Why is a fibre network so expensive before it earns anything?
Direct answer: because almost all of the cost is the dig, and the dig has to pass every home on a street before a single one can be sold to. Our consolidation report calculates that more than £17.4 billion has been invested in UK altnets since 2020, over £1,000 for every premises passed, up from under £400 in 2022 as the easy dense areas ran out.
The order of events is the whole problem. A network operator borrows money, digs a street, threads fibre through Openreach's ducts or its own, hangs it from poles, and fits a splice point outside every house. At that moment the street is "passed", the money is spent, and the revenue is zero. Only when a household signs up does a connection get made and a monthly payment begin. The industry's word for the first phase is build and for the second is fill, and the economics of the two are opposite: build is a fixed cost incurred up front, fill is revenue that arrives slowly and depends on decisions made by other people.
The cost of the dig varies enormously by place, which is why averages need care. Enders Analysis's telecoms director put the price at which anyone should be willing to buy an existing network at no more than £500 per home passed, noting that nexfibre can build new fibre for about that and overlay its own cable network for around £100 per home. The £1,000-plus average in our report is higher because it includes the cost of connecting customers, the overheads of a hundred separate companies, and the rising cost of the harder-to-reach premises built later. Whatever the figure on a given street, it is paid whether or not anyone signs up.
What does take-up mean, and why is 18% not enough?
Direct answer: take-up is the share of premises a network passes that actually buy a service over it. It is the only lever that turns a dig into revenue. INCA's State of the Altnets 2026 puts average altnet take-up at 18% of premises passed at the end of 2025. BT's July 2026 results put Openreach's at 40%.
Take-up matters more than any other number because the cost is fixed and the revenue is not. A network that passes 100 homes and connects 18 has spent exactly as much as one that passes 100 and connects 40, but each of the 18 paying customers is carrying more than twice as much of the dig. INCA's report frames the sector's shift as one from premises passed to actual connections, and lists customer acquisition as the thing its members are most concerned about. That is the right worry. The build is largely done: capex fell across the sector between 2024 and 2025, and premises passed grew 20% in 2025 while connections grew 32%. The question now is how fast the fill happens, and against what interest bill.
Take-up: share of premises passed that buy a service
The dig costs the same in both cases. The bar shows how much of it has a paying customer.
Sources: BT Group results for the quarter to 30 June 2026; INCA and Point Topic, State of the Altnets 2026, 11 March 2026. Altnet take-up rose two points in the year.
How does the maths work on one street?
Direct answer: with proportions, because the cost is fixed. The example below assumes nothing that is not sourced; it only shows what the take-up gap does to the revenue behind each pound of dig.
One street, one hundred homes, two networks
Illustrative. The point is the ratio, not the pounds.
The dig. Both networks pay to pass all 100 homes. Call that cost D. It is the same for both.
The customers. At Openreach's rate, 40 homes pay. At the altnet average, 18 do.
The dig per customer. Openreach: D divided by 40. Altnet: D divided by 18. Each altnet customer carries 2.2 times as much dig.
The interest. D was borrowed. If the loan was priced when the base rate was 0.1% and refinanced after it reached 5.25%, the annual interest on the same D rose many times over, and it is paid by the same 18 customers.
The overbuild. Now add a third network to the street. Three digs, one hundred homes, and the customers split three ways. At least one of the digs never pays back. That is not a forecast; it is division.
Two things follow from the example that are true of the real sector. The first is that take-up and time are the same thing: a network at 18% today and 30% in three years may be fine if the debt can wait, and in trouble if it cannot. The second is that a network's problem is rarely its customers, who are usually satisfied; INCA notes altnets consistently outscore the largest retailers on review platforms. Its problem is the ratio between the dig it has already paid for and the customers it has so far found, measured against a loan whose price changed after it was taken out.
What did interest rates do to the plan?
Direct answer: they changed the price of the money the networks were built with. The Bank of England's base rate was 0.1% from March 2020 until December 2021, when most of the build was financed. It then rose at fourteen consecutive meetings to 5.25% by August 2023, stayed there for a year, and has been cut in steps to 3.75%, where it has stood since December 2025. The debt raised in the cheap years has been serviced and refinanced in the expensive ones.
The funding numbers tell the story in order. INCA's earlier report estimated £7 billion committed to the sector in 2023 alone; its 2026 report records money actually raised at about £1 billion in 2023, £0.6 billion in 2024, then £3.2 billion in 2025. AlixPartners, writing in 2025, recorded debt volumes for altnet financing falling to around £170 million across a handful of deals by early that year, banks setting aside funds to cover potential defaults, and 47% of UK fibre companies facing refinancing a material proportion of their debt or equity by 2026. In the first half of 2025, it found, 96% of altnets surveyed were considering M&A or partnerships.
The 2025 recovery is real and it is selective. CityFibre's £2.3 billion package in July 2025, of which £500 million was equity and £1.76 billion debt and facilities, came from investors who could see a million connections and a national retailer signing up. INCA's own phrase is that funding rounds have favoured operators with proven take-up. The money did not come back to build; it came back to fill, and it came back to the networks that had already shown they could.
Funding raised by UK altnets, by year
As recorded by INCA. The 2025 figure went overwhelmingly to operators with proven take-up.
Source: INCA and Point Topic, State of the Altnets 2026, 11 March 2026.
What is the difference between EBITDA breakeven and actually making money?
Direct answer: EBITDA breakeven means the customers a network has now pay for its day-to-day running. It ignores the cost of the network already built and the interest on the debt that built it. KPMG reported that CityFibre and Community Fibre reached EBITDA breakeven in 2024, and that true cash-flow profitability remains distant for most.
This is the gap between the two numbers you will see quoted about the same company. A network can announce that it is EBITDA positive, meaning its revenue now exceeds the cost of running the network, the support desk and the sales team, and in the same year report a large loss, because the loss includes depreciation of the dig and interest on the loans. Enders Analysis calculated that the largest altnets lost £1.5 billion in 2024, up from £1.3 billion in 2023 and £755 million in 2022, driven by high interest rates and rising build costs; it warned that many may never make a profit and that the economics remain challenging even if debts are fully written off. Analysts citing Enders put the EBITDA margin needed just to break even on a cash basis at 35% or more, a level few operators have reached.
The consequence has already arrived for several operators. Lenders took control of Gigaclear in April 2026 with a haircut reported at up to 40% on nearly £1 billion of debt, and G.Network emerged from administration debt-free after its lenders absorbed the loss. In both cases the network kept running and the customers kept their service. What changed was who owned the asset and how much of the original money was gone.
Why does overbuild matter so much?
Direct answer: because two networks on one street each pay for a full dig and share the customers, and a third makes at least one of the digs unpayable. Ofcom reports a significant increase in premises with a choice of network, INCA's members say overbuild risk has risen sharply, and CityFibre and Sky have told the CMA that Netomnia and Virgin Media overlap across around 80% of Netomnia's footprint.
Overbuild was, in a sense, the policy. Ofcom's regulation of Openreach was designed to make it possible for rivals to build alongside it, and the physical infrastructure access rules that let them use Openreach's ducts made a second network affordable almost everywhere. For a household, two or three networks on the street is the best possible outcome: INCA reports that premises with access to four or more fibre networks consistently see lower average pricing than those served only by Openreach. For the networks, it is the reason the arithmetic does not close. A dig shared three ways at 18% take-up is a dig that cannot service its loan, which is why our consolidation report says the overlap map is the forecast.
What are the ways out?
Direct answer: fill faster, borrow cheaper, or combine. Filling faster means wholesale deals and anchor tenants. Borrowing cheaper means waiting for rates, which have fallen but not to where the loans were priced. Combining means the four exits our report describes, from a friendly merger to a lender takeover.
The most interesting lever is the first. ISPreview reported a CityFibre presentation putting its wholesale full fibre products at up to around 40% cheaper than Openreach's comparable ones. That is not generosity; it is arithmetic. A cheaper wholesale price brings in retailers, retailers bring customers, customers lift take-up, and take-up is the number the lenders look at. It is why Sky's arrival on CityFibre in 2025 mattered so much and why the anchor-tenant model is the hinge of the whole sector. INCA counted six consolidation deals agreed in 2025 and two announced early in 2026, nexfibre's purchase of Netomnia and Truespeed's combination with Freedom Fibre. The second is the shape of the friendly version: two businesses their announcement described as effectively unlevered, with 412,000 premises and 70,000 customers between them, combining to get scale without a lender in the room. The first is the shape of the other version, and it is in front of the CMA until December.
Is consolidation bad for customers?
Direct answer: for your connection, almost never. For your bill, it depends, and the evidence points both ways. What is certain is that your contract survives a change of owner and that any later change to your price or terms gives you a month's notice and a penalty-free exit.
- A network with a secure owner and cheaper debt can keep investing and keep prices stable.
- Larger platforms open to wholesale, so more brands sell over the same wire.
- A scaled challenger to Openreach is the parties' whole argument in the nexfibre case.
- Fewer networks on a street means less pressure on prices, and INCA's own data ties lower prices to more networks.
- Altnets have largely avoided mid-contract rises; a new owner may not.
- ISPreview reported in April 2026 that some altnets may have to raise prices to survive.
The one thing all four exits have in common is that the fibre keeps carrying broadband. A network is worth far more lit than dark, so nobody switches it off. That is why the practical advice below is about contracts and prices rather than about whether the lights go out.
What should you check if your provider is an altnet?
Direct answer: four things, and three of them take a minute. Whether your price is fixed or can rise mid-contract. Who owns the network under your street. Whether other brands sell over it. And what your rights are if the owner changes.
| Check | Why it matters | Where to look |
|---|---|---|
| Is your price fixed for the term? | Many altnets promise no mid-contract rises. A change to that promise after a takeover gives you one month's notice and a right to leave, but only if you notice. | Your contract's price terms. The provider's help pages. |
| Who owns the network? | The brand you pay and the company that owns the fibre may differ, and a sale can move one without the other. | The provider's website footer or about page; our provider directory. |
| Do other brands sell over it? | If yes, you can change provider without a new install. If no, leaving the provider means leaving the network. | A postcode check. If several brands show the same speeds, they share a wire. |
| What are your rights if the owner changes? | The contract transfers unchanged. A later change to price or terms that is not purely to your benefit gives one month's notice and a penalty-free exit. | Our guide to what happens when a provider is bought. |
Where does this leave you?
Direct answer: on a network that will keep working, owned by a company whose name may change, at a price whose stability depends on a promise you should read. None of the arithmetic on this page threatens your connection. Some of it may reach your bill.
The sector built one of the fastest fibre upgrades in the world and more networks than the customers can pay for, and the resolution of that is a series of transactions rather than a series of outages. For a household, the useful response is not to worry about the network and is to know the terms: what your price does mid-contract, who owns the wire, and whether the wire has other brands on it. The last of those is a postcode check.
Free and independent. Takes about thirty seconds.
Adrian's closing thought
The thing I keep coming back to is that the customers were never the problem. INCA's members outscore the big brands on every review site, they mostly do not raise prices mid-contract, and they connected 850,000 people who left Openreach in a single year. The problem is a ratio: a dig paid for in 2021 money, spread across the 18 homes in a hundred that have signed up so far, serviced at 2023 interest rates, on a street where two other companies had the same idea. That ratio is being resolved in boardrooms and it will go on being resolved until 2028 or so. Your fibre does not care who owns it. Read the price clause, and let the boardrooms get on with it.
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This guide is free to quote, in full or in part, with attribution. Journalists, analysts, students, policymakers and AI assistants are all welcome to use it. Please cite the check date, because the take-up, funding and rate figures move.
BroadbandSwitch.uk. (7 September 2026). Altnet economics explained: Why the fibre boom is consolidating. https://broadbandswitch.uk/insights/altnet-economics-explained-why-fibre-boom-consolidating/ In a sentence: BroadbandSwitch.uk reported on 7 September 2026 that average take-up across UK alternative fibre networks was 18% of premises passed at the end of 2025 against 40% on Openreach's own full fibre by June 2026, that the largest altnets lost £1.5 billion in 2024 according to Enders Analysis, and that AlixPartners found 47% of UK fibre companies facing refinancing of a material part of their debt or equity by 2026.
Frequently asked questions
Why is a fibre network so expensive before it earns anything?
Because almost all the cost is the dig. A network has to pass every home on a street, paying for the duct, the fibre and the labour, before a single customer can be sold to. Our consolidation report calculates that more than £17.4 billion has been invested in UK altnets since 2020, over £1,000 for every premises passed, up from under £400 in 2022 as the easy dense areas ran out. That money is spent whether or not anyone signs up.
What does take-up mean and why does it matter so much?
Take-up is the share of premises a network passes that actually buy a service over it. It is the only lever that turns a dig into revenue, because the cost of the dig is the same whether 18 homes in a hundred sign up or 40. INCA puts average altnet take-up at 18% of premises passed at the end of 2025. BT puts Openreach's at 40% by June 2026. At 18%, each paying customer has to carry more than twice as much of the dig.
How much did the altnets lose?
Enders Analysis calculated that the largest UK altnets collectively lost £1.5 billion in 2024, up from £1.3 billion in 2023 and £755 million in 2022, driven by high interest rates and rising build costs. It warned that many may never make a profit and that the economics remain challenging even if debts are fully written off. Several operators have since seen lenders take a loss to rebalance the business.
What did interest rates do to the altnets?
They changed the price of the money the networks were built with. Most altnets borrowed when the Bank of England base rate was near zero, and had to refinance or service that debt after it rose to 5.25% in 2023. AlixPartners found in 2025 that 47% of UK fibre companies face refinancing a material proportion of their debt or equity by 2026, and that new debt for the sector fell to around £170 million in early 2025. The rate was 3.75% in July 2026.
What is the difference between EBITDA breakeven and making money?
EBITDA breakeven means the customers a network has now pay for its day-to-day running costs. It does not count the cost of the network already built or the interest on the debt that built it. KPMG reported that CityFibre and Community Fibre reached EBITDA breakeven in 2024, and that true cash-flow profitability remains distant for most. Enders has said EBITDA margins of 35% or more are needed just to break even on a cash basis.
Why does overbuild matter?
Because two networks on one street each pay for a full dig and share the customers. Ofcom reports a significant increase in premises with a choice of network, INCA's members rank overbuild risk as having risen sharply, and CityFibre and Sky have told the CMA that Netomnia and Virgin Media overlap across around 80% of Netomnia's footprint. Where three networks pass the same homes, at least one of the digs never pays back.
Has the money for altnets run out?
No, but it has become selective. INCA records funding of about £1 billion in 2023, £0.6 billion in 2024 and £3.2 billion in 2025. The 2025 money went to operators with proven take-up, led by CityFibre's £2.3 billion package in July 2025, and it is being spent on connecting customers rather than passing new homes. Capex across the sector fell between 2024 and 2025 as the build phase ended.
Will consolidation cut my broadband off?
Almost never. A fibre network is worth far more lit than dark, so a merger, an acquisition, an administration or a lender takeover all leave the fibre carrying broadband. What changes is the name on the bill and sometimes the price. Your existing contract transfers to the new owner unchanged, and any later change to your price or terms gives you one month's notice and a penalty-free exit under Ofcom's rules.
Will prices go up after consolidation?
Nobody knows, and the evidence points both ways. INCA reports that altnets have largely avoided inflation-linked mid-contract rises and that premises with four or more fibre networks see lower average pricing. ISPreview reported in April 2026 that some altnets may have to raise prices to survive, and Openreach's average revenue per line rose 7% in a year. Fewer networks usually means less pressure on prices; a stronger challenger can mean more.
What should I check if my provider is an altnet?
Four things. Whether your contract fixes the price or allows mid-contract rises. Who owns the network under your street, because the retail brand and the network are sometimes different companies. Whether other providers sell over the same network, which gives you somewhere to go without a new install. And what your notice and exit rights are if the owner changes, which our guide to what happens when a provider is bought sets out.
Is 18% take-up bad for a young network?
Not by itself. Take-up rises as a network ages, and INCA notes it grew two points in a year. Openreach's 40% has taken years and it is still climbing. The problem is not that 18% is low; it is that the debt was borrowed against a faster climb than has happened, at interest rates lower than those now being paid. Time and rates, not take-up alone, are what turned a plan into a refinancing problem.
Why do altnets sell wholesale access more cheaply than Openreach?
Because filling the network is worth more to them than the margin on each line. ISPreview reported a CityFibre presentation putting its wholesale full fibre products at up to around 40% cheaper than Openreach's comparable ones. A cheaper wholesale price brings in retailers, which brings in customers, which lifts take-up, which is the lever that services the debt. It is also why anchor tenants matter so much.
References
- AlixPartners. (2025). Commercial reality check raises consolidation prospects for UK altnets. Retrieved 7 September 2026, from https://www.alixpartners.com/insights/102lr2g/commercial-reality-check-raises-consolidation-prospects-for-u-k-altnets/
- Bank of England. (2025, September 18). Monetary policy summary and minutes: September 2025. Retrieved 7 September 2026, from https://www.bankofengland.co.uk/monetary-policy-summary-and-minutes/2025/september-2025
- Barchart. (2026). Truespeed and Freedom Fibre announce strategic combination. Retrieved 7 September 2026, from https://www.barchart.com/story/news/161729/truespeed-and-freedom-fibre-announce-strategic-combination
- Bratby Law. (2026, June 14). UK fibre consolidation: Transactions outlook. Retrieved 7 September 2026, from https://bratby.law/uk-fibre-consolidation-transactions/
- BroadbandSwitch.uk. (2026, July 13). The Great Consolidation: Forecasting the UK fibre shake-out (Report No. 27). Retrieved 7 September 2026, from https://broadbandswitch.uk/reports/the-great-consolidation/
- BT Group. (2026, July 23). Results for the three months to 30 June 2026. Retrieved 7 September 2026, from https://www.bt.com/content/dam/bt-plc/assets/documents/investors/financial-reporting-and-news/quarterly-results/fy27/q1/q1-fy27-trading-update.pdf
- everyfibre. (2026). The great altnet shake-out: UK fibre's consolidation wave. Retrieved 7 September 2026, from https://everyfibre.co.uk/articles/uk-altnet-consolidation/
- FBRE.uk. (2026, June 4). UK AltNet Tracker 2026: Premises, customers, funding. Retrieved 7 September 2026, from https://fbre.uk/research/uk-altnet-tracker
- INCA. (2026, March 11). State of the Altnets 2026. Retrieved 7 September 2026, from https://inca.coop/state-of-the-altnets-2026/
- ISPreview. (2025, November 24). Enders Analysis warns largest UK broadband altnets lost £1.5bn in 2024. Retrieved 7 September 2026, from https://www.ispreview.co.uk/index.php/2025/11/enders-analysis-warns-largest-uk-broadband-altnets-lost-1-5bn-in-2024.html
- ISPreview. (2026, April 15). Alternative UK broadband networks may have to hike prices to survive. Retrieved 7 September 2026, from https://www.ispreview.co.uk/index.php/2026/04/alternative-uk-broadband-networks-may-have-to-hike-prices-to-survive.html
- KPMG. (2025, June). Home stretch for UK fibre: Navigating the consolidation wave. Retrieved 7 September 2026, from https://assets.kpmg.com/content/dam/kpmgsites/uk/pdf/2025/06/home-stretch-for-uk-fibre.pdf.coredownload.inline.pdf
- money.co.uk. (2026, July 30). Bank of England base rate 2026: Latest updates. Retrieved 7 September 2026, from https://www.money.co.uk/mortgages/bank-of-england-base-rate
- Mortgage One. (2026, July 30). Bank of England base rate history: 50 years. Retrieved 7 September 2026, from https://www.mortgageonefinance.co.uk/bank-of-england-base-rate-history
- Ofcom. (2025, March 20). Consultation: Promoting competition and investment in fibre networks: Telecoms Access Review 2026-31. Retrieved 7 September 2026, from https://www.ofcom.org.uk/phones-and-broadband/telecoms-infrastructure/consultation-promoting-competition-and-investment-in-fibre-networks-telecoms-access-review-2026-31
- Opensignal. (2026, July). UK altnets built fibre, now customers are switching: Subscriber analytics Q2 2026. Retrieved 7 September 2026, from https://insights.opensignal.com/2026/07/uk-altnets-built-fibre-now-customers-are-switching-opensignal-subscriber-analytics-q2-2026/dt
- Point Topic. (2024, April 25). Annual INCA / Point Topic altnet sector report. Retrieved 7 September 2026, from https://www.point-topic.com/post/annual-inca---point-topic-altnet-sector-report
- StatuteRates. (2026, August 25). Bank of England Bank Rate [Recording Bank of England series IUDBEDR]. Retrieved 7 September 2026, from https://statuterates.com/rates/boe-bank-rate/
- telecoms.com. (2025, November 24). Consolidation looms as UK altnets losses reach £1.5 billion. Retrieved 7 September 2026, from https://www.telecoms.com/fibre/consolidation-looms-as-uk-altnets-losses-reach-1-5-billion
- thinkbroadband. (2026, March 11). INCA State of the Altnet report says altnets moving towards monetisation. Retrieved 7 September 2026, from https://www.thinkbroadband.com/news/inca-state-of-the-altnet-report-says-altnets-moving-towards-monetisation
Written by Adrian James, Broadband Editor at BroadbandSwitch.uk (LinkedIn). Reviewed by Dr Alex J. Martin-Smith (LinkedIn). Published 7 September 2026, last verified 7 September 2026. The worked example is illustrative and uses proportions only. Figures are as reported by the named sources at the dates given. This guide is information, not investment or financial advice. BroadbandSwitch.uk has no commercial relationship with any network operator.