At the Farnborough International Airshow's finance summit this week, senior bankers made a coordinated case: governments cannot pay for the defence buildup on their own, and institutional investors need to commit capital at scale.

Cathal Deasy, global co-head of investment banking at Barclays, put it plainly: "Public spending will not be enough, and we do need to mobilise private capital at scale," adding that governments need to move faster and provide policy clarity.

It is worth knowing who is speaking. These are banks and asset managers who earn fees arranging exactly the capital they are calling for, at an industry event designed to attract it. That does not make the argument wrong. It does mean it should be tested rather than transcribed.

The shift is real

Whatever one makes of the framing, the change in institutional posture is genuine and measurable.

The summit drew more than 600 finance delegates, roughly three times the previous year, including Goldman Sachs, J.P. Morgan, Citigroup, Barclays, Blackstone and Carlyle, alongside sovereign wealth funds.

Amin Mansour, a vice chairman at ING, said the bank now has around 50 bankers working across sectors on defence transactions, against "very few five years ago." For a European lender, that is a substantial reallocation of a scarce resource.

Where the executives say the bottleneck is

Notably, the people involved do not mostly describe a shortage of willing money. They describe difficulty getting it into the right place.

Ephraim Rudman, a financial institutions group partner at Apollo, identified the problem as "getting the capital into the supply chain which is challenging and which does create bottlenecks."

That is a different complaint from "there is not enough capital." The supply chain below the prime contractors consists of many small and mid-sized specialist manufacturers, often family-owned, frequently single-source for a component, and generally too small for institutional cheque sizes. Scaling them requires firm multi-year orders to underwrite the investment, and those orders come from defence ministries.

What the market is saying

Here is the fact that sits awkwardly with the funding-gap framing.

Aerospace and defence equities are up about 1.3% since the start of 2026, against roughly 8% for the STOXX 600 over the same period. The sector is underperforming the broad European market during what is supposed to be a generational rearmament.

If capital availability were the binding constraint on a sector with guaranteed demand, you would expect the opposite: investors bidding up the listed vehicles that already have the contracts, the factories and the security clearances. Instead the sector lags.

The more parsimonious reading is that investors are not short of appetite; they are unconvinced about execution and timing. Defence revenue depends on procurement decisions that are slow, politically reversible and frequently rephased. An order announced is not an order funded, and a budget commitment made by one government can be revisited by the next.

The structural counter-argument

There is a further objection to the "gap" language, and it is not a trivial one.

Defence output is bought almost entirely by governments. There is no meaningful private end market for main battle tanks. That makes a shortfall in defence capacity a question about how much states choose to spend and how quickly they contract, not a failure of capital markets to allocate.

Framed that way, "mobilise private capital" means something more specific than it sounds: it means asking investors to finance capacity ahead of firm orders, taking procurement risk that governments have historically carried. Whether investors should take that risk depends entirely on the price and on contractual protections, which is a negotiation, not a market failure.

The ESG argument has also weakened as a explanation. Exclusions on weapons manufacturers were a genuine constraint on some European institutions, but a number have revisited those policies as the security environment changed, which is part of why ING can now staff 50 bankers to the sector.

What would actually resolve it

The test is straightforward and observable. If governments issue long-dated, firm, funded orders that reach beyond the primes into the supply chain, capital will follow, because the risk becomes underwritable. If they issue statements of intent, it will not, regardless of how many summits are held.

Watch order backlogs and contract durations at the listed primes rather than the rhetoric. Those are the numbers that tell you whether the demand is real enough to finance.