Disclaimer / Methodological Note: This report has been compiled exclusively on the basis of public sources only. It presents a synthesis of factual information, official data, and documented positions from EU institutions, international organisations, press releases and independent research bodies. It does not express an opinion, political judgement, or recommendation of its own.

Executive Summary

This report set out to test whether Europe's small stock market capitalisation, relative to the size of its economy, is itself the structural cause of Europe's weaker innovation and competitiveness. Europe's market capitalisation is genuinely, substantially smaller than America's — roughly 50-60% of GDP versus the United States' 224% as of early 2026. That fact is not in dispute.

What is in dispute is whether raw size is the right diagnosis. After working through the academic finance-growth literature, EU policy diagnostics, and detailed comparative research into how European capital markets are built, funded, and governed, the evidence supports a more precise conclusion. The academic literature most directly on point finds that market liquidity, not raw size, is the more robust predictor of growth. The size gap is a symptom; the more useful, more actionable findings sit underneath it.

Five structural findings carry the report:

- institutional capital is flowing disproportionately toward the US and the gap is widening;

- Europe's retail investors save as much as their US counterparts but hold far less in equities, and the EU's push to close that gap is arriving before retail protection has caught up; -

- Europe's exchanges, post-trade infrastructure, and regulatory supervision remain fragmented across national lines, with industry given only an advisory voice in the one body meant to unify supervision; -

- Europe's growth-company listing tiers privatise admission vetting to commercially conflicted intermediaries; -

- and those same tiers are, if anything, adequately regulated but poorly labelled — carrying institutional-sounding names that do not warn retail investors the way America's “Pink Sheets” label does.

The raw size gap is real but is not, on its own, what the strongest research identifies as causal. Fragmentation, capital flows, retail protection, and disclosure design are.

1. The Real Question: Size versus Liquidity

Market capitalisation as a share of GDP is a widely used but blunt proxy. It is easy to calculate and easy to compare across countries, which is why it dominates policy discussion. The foundational academic literature draws a sharper distinction than the headline number suggests. Ross Levine and Sara Zervos's 1998 study, still the most cited paper in this field, found a significant link between stock market development and long-run growth — but subsequent re-examination, including by Levine himself, found that market size specifically is not a robust predictor of growth; market liquidity is. A large but illiquid, fragmented market does not reliably deliver the growth benefit that a smaller, well-integrated, highly liquid market can.

This reframes the policy question. It is not “how do we make the number bigger,” but “why is European liquidity and capital mobilisation structurally weaker” — a narrower and more tractable question, and the one this report answers.

The gap itself is not newly discovered. Mario Monti's 2010 report to the European Commission, A New Strategy for the Single Market, already diagnosed a fragmented internal market as a drag on European growth, fourteen years before Mario Draghi's 2024 EU competitiveness report put a concrete figure on the consequence today: an estimated €750-800 billion annual investment gap relative to what Europe needs to fund productivity growth, digitalisation, defence, and the green transition. Draghi ties this explicitly to underdeveloped capital markets rather than a shortage of underlying savings — European households save at high rates, but the money is disproportionately held in bank deposits rather than invested in equity. That two landmark reports, fourteen years apart, reach the same diagnosis says something about how hard this problem is to fix.

2. Where the Capital Doesn't Go: Institutional Home Bias

Europe's size gap is compounded by a demand-side pattern: global institutional capital is disproportionately allocated to US equities, and the imbalance is widening, not closing. A April 2026 Bruegel policy brief (Schoenmaker) found the European market share of US-based asset managers rose from 40% to 47% between 2021 and 2026, driven partly by consolidation — Goldman Sachs's 2022 acquisition of the Netherlands' NN Investment Partners, and US-based Nuveen's 2026 takeover of UK-based Schroders. Globally, North American asset managers' share of worldwide assets under management rose from 73% to 78% between 2021 and 2025, while Europe's fell from 21% to 17%.

The same research quantifies the bias directly. The “Big Three” passive managers — BlackRock, Vanguard, State Street — hold a median 24% stake in S&P 500 companies; in European companies, that figure is only 5-16%. Free-float differences (88% of shares tradeable in the US versus 71% in Europe) explain only part of the gap; most of it reflects a genuine investor choice, not just a difference in what is available to buy.

Why the choice happens

Economists call this pattern “home bias,” though in this case it is really an away bias — European investors, too, favour US stocks. Three mechanisms explain most of it, and none require anyone to be actively choosing against Europe:

• Familiarity runs backwards. US company news, analyst coverage, and financial media dominate what investors everywhere read, so large US companies often feel more familiar to a European fund manager than companies in the next EU country over.

• Index investing is mechanical. Most ordinary investing now happens through index funds that mirror the market's existing composition. If US companies make up roughly two-thirds of global market value, roughly two-thirds of every dollar in a “world stock market” fund flows to the US automatically — a self-reinforcing effect, independent of any investor's view on Europe.

• EU insurance rules penalise equity-holding. Solvency II requires European insurers to hold close to €0.39 of capital “safety cushion” for every €1 of stock, a materially higher charge than for bonds and with no equivalent constraint on US insurers, discouraging equity holdings — European and American alike.

• Supervision is nationally siloed. Large US asset managers typically run their EU-wide business out of one hub, usually Luxembourg or Ireland, for favourable local rules. Because each national regulator mostly watches only its own market, no single supervisor sees the EU-wide pattern — making the trend harder for Europe to notice or respond to.

This pattern is changing more than ownership — it is changing governance. European asset managers voted in favour of environmental and social shareholder resolutions roughly 86% of the time in 2024; US managers' support for the same resolutions fell from 49% in 2021 to just 17% in 2024. One caveat: 2025-2026 fund flows show a real tactical rotation toward Europe, with non-US developed markets outperforming the S&P 500 through much of 2025 — but this starts from the extreme concentration above, so a genuine reversal would take considerable time to close the underlying gap.

Institutional investors have confirmed this diagnosis in their own words, not just their allocations. BlackRock's September 2025 white paper, Roadmap to Growing European Capital Markets, found that cross-border funds already make up over half of total European fund assets — evidence of what the Single Market can achieve when it works — while arguing that further streamlining of cross-border passporting is still needed, and separately highlighting a large R&D-spending gap between the largest US and European companies. The Jacques Delors Centre notes, consistent with the mechanism above, that European institutional investors rarely allocate to venture capital funds that could finance young, innovative companies, echoing the financial-dependence theory discussed in the closing literature review.

3. Where the Capital Comes From: The Retail Gap and Its Protection Problem

Institutions dominate equity ownership on both sides of the Atlantic — roughly 78-80% of US market capitalisation (Russell 3000/S&P 500) — but the retail gap between the US and EU is itself substantial. US household equity exposure runs at 38-46% of household financial assets; EU households held only about 17% of assets in financial securities as of 2021, against 43% in the US, with EU households instead holding 30-35% of assets in low-yield bank deposits versus 10-15% in the US — despite comparable or higher EU savings rates (Germany over 20%, France over 17%). The Association for Financial Markets in Europe puts a stark number on the consequence: average per-person savings held in capital markets instruments run around $290,000 in the US, dramatically higher than in the EU.

The money exists; it simply is not reaching equity markets. The EU is now trying to change that — and its own diagnostics show the protective infrastructure has not caught up. The EU's Retail Investment Strategy explicitly states its goal is to give retail investors “the same level of information, treatment and protection as institutional investors” — a direct admission that they do not currently have it. Supporting EU data shows retail investors pay fees 40% higher than institutional investors on average, and only 38% of EU consumers are confident the investment advice they receive is primarily in their best interest.

Institutional investors have research staff, direct company access, and negotiating leverage that let them discount weak public disclosure; retail investors relying on a lightly-vetted “inclusion document” do not.

The timing compounds the problem. The EU is pushing retail savings toward markets through the Retail Investment Strategy and the broader Savings and Investments Union at precisely the moment institutional capital is drifting toward the US (Section 2) — leaving European companies short of both sources of capital at once. This retail push is also arriving alongside significant growth-company listing activity on the MTF/SME Growth Market tier, the segment with the lightest disclosure vetting of any public-market category, discussed in Section 5. Nobody designed this combination maliciously, but the mismatch between where the EU wants retail money to go and where retail protection is weakest is real and documented in the EU's own materials.

4. The Infrastructure Problem: Fragmentation

4.1 Thirty-five exchanges, one market that isn't

This is where the case for a genuine structural handicap is strongest, and it is not really a market-cap question — it is an infrastructure and political-economy question. Europe operates roughly 35 exchanges for listings and 41 for trading, run by around 22 different exchange groups, alongside nearly 40 separate central counterparties and central securities depositories. The US, by contrast, operates three exchange groups and 16 trading venues. Europe's entire equity market is less than half the size of the US market but carries three times as many exchange groups and more than ten times as many listing venues.

Research from the financial-sector group New Financial finds that smaller exchanges which are part of larger groups perform better than standalone exchanges — consolidation has a measurable liquidity benefit — yet consolidation has repeatedly stalled, for reasons that are political rather than technical:

• National-champion politics. A country's stock exchange functions similarly to a national airline in political symbolism — a marker of economic sovereignty that governments resist ceding, independent of the efficiency case for merging.

• Historical “concentration rules.” France, Italy, and Spain, among others, historically required domestic trades to route through the domestic national exchange, deliberately insulating local infrastructure from competition.

• Post-trade fragmentation compounds exchange fragmentation. Even where exchanges merge, clearing and settlement systems often remain nationally siloed — a separate and harder integration problem.

This fragmentation is a documented contributor to a falling number of European listed companies (down 17% over the past decade, per New Financial's research) and to Europe's shrinking share of global IPO activity — a far more direct and better-evidenced link to competitiveness than the aggregate market-cap figure alone. AFME's 2025 competitiveness report reaches the same conclusion from the regulatory side: despite record bond issuance, the EU has made only limited progress closing the gap with other major capital markets, citing continued fragmentation and subdued IPO activity.

4.2 Fragmented supervision, and industry's advisory-only seat

Fragmentation extends to regulatory supervision itself. EU securities law has always relied on public national regulators — the AMF in France, BaFin in Germany, Consob in Italy, the FSMA in Belgium, and so on — with no real equivalent to the American model of industry-funded, front-line self-regulation. The actual live debate in Europe is whether supervision should remain with 27 national regulators or be centralised under the European Securities and Markets Authority (ESMA), and it is an active, unresolved political fight, not a settled preference.

In May 2026, the EU's six largest economies (Germany, France, Italy, Poland, Spain, and the Netherlands, representing roughly 70% of the EU's population) agreed to back gradually transferring supervision of major market infrastructure to ESMA. But EU finance ministers remained deadlocked on the specifics as recently as May-June 2026, with national regulators actively resisting the transfer of authority — Germany has historically been especially cautious about ceding supervisory power to Brussels or Paris. A smaller group of countries, led by Ireland and Luxembourg, resists centralisation for a more specific reason: both host a disproportionate share of Europe's investment fund industry precisely because of favourable, locally-supervised regimes, and a single EU supervisor would reduce that competitive advantage. The centralisation fight is at least partly a fight over which national financial centres keep their current advantages, not a clean debate about efficiency versus sovereignty in the abstract.

Within this system, financial market participants have a voice but not a vote. ESMA's actual decision-making body, the Board of Supervisors, is composed entirely of the heads of the 27 national regulators, with binding authority over ESMA's technical standards, opinions, and guidelines. The only body where industry participants sit is the Securities and Markets Stakeholder Group, a 30-member advisory panel — roughly a third of its seats go to financial market participants, alongside consumer representatives, SME representatives, employee representatives, and academics — that can submit opinions and meets with the Board of Supervisors twice a year, but cannot vote on or block any ESMA decision.

5. The Growth-Tier Problem: Vetting and Labelling

This is the strongest, most specific, and most consistently documented finding in this research, and it has two parts: who checks a growth-company listing on the way in, and whether investors are told how little checking that was.

5.1 Admission is privatised

Multilateral Trading Facilities (MTFs) are frequently described as poorly supervised — and on the specific point that matters most, how a company actually gets admitted to the market, that description holds up. MTF operators themselves are licensed under MiFID II, but companies listed on their growth-company segments go through meaningfully lighter, privatised admission vetting rather than the direct regulatory review of a full prospectus that a main “Regulated Market” listing requires. The same design recurs across the EU's largest markets.

Deutsche Börse's own documentation is explicit that BaFin's oversight of Scale is limited to market abuse and insider trading rules, not admission review; Euronext Access is described in Euronext's own listing materials as “not regulated under the EU Directive” at all — the most direct language found anywhere in this research.

The fair US comparison is not Nasdaq Capital Market, which is a fully SEC-registered exchange, but the OTC Markets Group — specifically its OTCQX, OTCQB, and Pink tiers — none of which are SEC-registered exchanges at all. The SEC's own investor guidance warns directly that OTC and Pink Sheets stocks are among the riskiest and most open to manipulation, naming pump-and-dump schemes as the defining danger of that tier. Comparing light-tier to light-tier changes the conclusion in an important way: the US does not come out looking obviously cleaner once the comparison is corrected. Pink Sheets arguably carries a worse fraud reputation than Europe's growth-company tiers.

5.2 But Europe doesn't label the risk

If there is one finding that best captures the actual difference between European and American markets, it is this one — and it is not about how much regulation exists, but about how visibly that risk is signalled to the people relying on it.

The US visibly brands its risk tiers. Any American investor, professional or amateur, recognises “Pink Sheets” as shorthand for buyer-beware — the name itself functions as a warning label. Europe's equivalent tier carries the opposite kind of name: “Euronext Growth,” “Scale.” These sound institutional, established, and safe. Nothing about the branding tells an ordinary investor that admission was vouched for by a paid, conflicted private intermediary rather than reviewed directly by a public regulator.

A retail investor with no other information is far more likely to correctly judge their risk reading “Pink Sheets” than reading “Euronext Growth” — and per Section 3, retail investors are exactly the population the EU is now actively recruiting into these markets.

Both the US and European light-touch tiers have real gaps in oversight. But the US at least names its risk tier in a way that functions as a public warning. Europe's naming convention does the opposite — it borrows the credibility of the main market's brand (“Euronext,” “Deutsche Börse”) for a product with a meaningfully different risk profile.

6. What's Already Been Fixed

Not every point of European regulatory friction is a permanent fixture, which is itself a useful data point. Historically, EU prospectuses had to be translated into the language of each host member state — a real and well-documented deterrent to cross-border listings. This has already been resolved: under the EU Listing Act, with the amended Prospectus Regulation taking effect 5 June 2026, issuers may now draw up a prospectus in English only, at their own discretion, regardless of whether the offering is domestic or cross-border, with only the short summary potentially requiring local-language translation.

This demonstrates that identified points of friction in European capital markets can and do get resolved once sufficient political will exists — relevant context for how to weigh the currently unresolved fights over exchange consolidation and ESMA centralisation discussed in Section 4.

Conclusion

Europe's aggregate market capitalisation gap relative to GDP is real and large, but the literature most directly on point finds liquidity and institutional quality, not raw size, to be the more robust predictors of growth. Two specific statistical claims initially offered in support of a strong causal story could not be verified and appear to have been fabricated; they are omitted from this report and flagged in the closing literature review.

What the evidence supports, with considerably more confidence, is five narrower and more actionable findings:

• Global institutional capital is flowing disproportionately, and increasingly, toward the US rather than Europe — a widening rather than closing gap, confirmed independently in institutional investors' own policy submissions.

• Europe's retail investors save at least as much as their US counterparts but hold far less in equities, and the EU's push to close that gap is arriving alongside its own admission that retail investors lack institutional-grade protection.

• Europe's exchanges, post-trade infrastructure, and regulatory supervision remain fragmented across national lines — a problem diagnosed as early as 2010 and still unresolved — and the supranational regulator meant to unify supervision gives industry only an advisory voice, not a vote.

• Europe's growth-company listing tiers share a consistent, EU-wide design choice to privatise admission gatekeeping to commercially conflicted intermediaries.

• Those same tiers are not meaningfully less regulated than their closest US equivalents, but they are far less clearly labelled for risk — borrowing the credibility of established exchange names rather than warning retail investors the way America's “Pink Sheets” label does.

These are more precise, more actionable findings than “market cap is too small,” and they point toward different policy fixes: consolidating infrastructure, closing the retail-protection gap before recruiting retail money into it, and giving growth-tier listings a label that tells investors what it actually is.

Annex: The Academic Literature

This annex deliberately excludes several sources that surfaced during this research but could not be verified, including a claimed “2026 meta-analysis of 30 studies” and a claimed World Federation of Exchanges finding on two-way versus one-way causality by income level. Neither could be located despite repeated targeted searching, and both carried statistical specificity — exact percentages, exact study counts — that is a common signature of fabricated citation. They are omitted rather than repeated.

What holds up

• Levine & Zervos (1998), American Economic Review, and the subsequent literature confirm a real association between financial market development and growth — but subsequent re-examination, including by Levine himself, found liquidity rather than size to be the more robust predictor of growth.

• Rajan & Zingales (1998), “Financial Dependence and Growth,” provides the most precise theoretical mechanism connecting equity markets to innovation specifically: industries that structurally depend on external finance — young, R&D-intensive, asset-light firms, since they lack the collateral banks require — grow disproportionately faster in countries with deeper financial markets. This is a firm-type-specific claim, not a generic “bigger market, more growth” claim, and it is the strongest theoretical bridge between Europe's capital markets and its innovation gap specifically.

• Li (2025), “Valuation Driven Innovation,” Asia-Pacific Financial Markets, found that individual companies with higher market valuations patent more, using mutual fund flow shocks to establish causality. This is a real, credible paper — but it studies individual firm valuation, not aggregate national market capitalisation, and does not support a country-level claim about Europe's total market size.

• A 20-country mediation analysis found partial mediation of market capitalisation between GDP growth and control variables (FDI, capital formation) using one statistical method — but the same paper's own Granger causality test failed to reject the null hypothesis that market capitalisation does not cause GDP growth (p = 0.207). A paper that finds a positive result by one method and a null result by another is genuinely mixed evidence, not confirmation.

The honest synthesis: the literature supports a qualified, mechanism-specific claim — deep, liquid equity markets disproportionately help external-finance-dependent innovative firms — rather than a blanket claim that market size predicts national innovation output. Causality in the broader finance-growth relationship also remains genuinely disputed; some studies find financial development drives growth, others find growth drives financial development, and several argue both directions reinforce each other simultaneously.