How Switzerland’s SNB quietly amassed a $167bn US stock portfolio—with $42bn in Big Tech alone

ZURICH —The Swiss National Bank (SNB) has long been known as the steward of a famously strong currency and a famously cautious economic culture. But new disclosures show another, far less traditional identity: one of the world’s biggest investors in American technology stocks. Regulatory filings for the quarter ended June 30, 2025 list roughly $167 billion in U.S. equities spread across more than 2,300 positions, with over $42 billion concentrated in just five companies—Amazon, Apple, Meta, Microsoft and Nvidia—making the Swiss central bank an unlikely power in Silicon Valley.

The scale is startling. The SNB’s U.S. stock book is larger than many sovereign wealth funds’ public‑equity sleeves and rivals some of Wall Street’s marquee asset managers. Its single biggest holding, chipmaker Nvidia, is now an anchor of the portfolio thanks to the AI boom, while long‑standing stakes in Microsoft and Apple have compounded over years of steady purchases and market gains. Amazon and Meta round out a top tier that—collectively—accounts for a quarter of the SNB’s disclosed U.S. holdings.

A monetary policy tool, not a moonshot

The SNB’s rise as a tech whale is not a bet placed by a swashbuckling stock‑picker. It is the by‑product of a decade‑plus struggle to manage the Swiss franc. Because global investors treat the franc as a safe‑haven, capital floods into Switzerland in times of stress, pushing the currency up and threatening deflation at home. To blunt those pressures, the SNB built one of the world’s largest foreign‑exchange reserve piles and invested much of it abroad—unlike most central banks, which focus on domestic bonds. The result is an enormous, mostly passive portfolio of foreign government bonds, corporate debt and equities, with U.S. stocks the single largest and most liquid piece.

Officials stress that portfolio construction follows rules, not hunches. The bank excludes Swiss equities to avoid conflicts of interest and steers clear of banks and weapons makers under its own guidelines. For equities it uses broadly diversified indices and refrains from activist behavior. Yet in market terms, size alone confers influence: when the SNB rebalances, whole sectors feel the flow.

A different kind of ‘state investor’

Comparisons with Norway’s $1.6 trillion sovereign wealth fund are inevitable but imperfect. Norway’s fund exists to transform oil wealth into a diversified financial asset for future generations, with an explicit return target and parliamentary guardrails. The SNB’s balance sheet, by contrast—roughly CHF 760–800 billion over the past year—exists to serve monetary policy. Its equity sleeve is a tool to manage liquidity and currency strength, not to chase alpha. That distinction has policy consequences. Losses and gains show up in the SNB’s results, not a fiscal stabilization fund, and dividend flows or capital gains are not the objective; stability is.

The AI boom made the top five unavoidable

If the SNB is largely passive, why is it so concentrated in Big Tech? Partly because global market‑cap indices are. The extraordinary run‑up in U.S. mega‑caps—supercharged by the AI investment cycle—has swollen their index weights. Even without ‘making a call’, any investor who tracks or hugs those indices ends up owning a lot of Apple, Microsoft and Nvidia. The SNB is no exception. As Nvidia rocketed and software giants re‑rated on AI optimism, their share of the SNB’s disclosed book grew too.

Quiet giant, public scrutiny

As the SNB’s positions have ballooned, so has debate at home. Supporters argue that heavy foreign diversification is essential to neutralize franc pressure and to protect the domestic economy. Critics counter that the central bank is now deeply exposed to a narrow slice of the U.S. market and to the policy and regulatory winds that come with it—from antitrust to export controls on advanced chips. They also worry about optics: a Swiss monetary authority collecting windfalls—or paper losses—on California’s fortunes.

There is also a governance question. The SNB maintains it is a policy institution, not an active asset manager, and that its equity holdings are implemented through simple, rules‑based mandates. But rules still require choices: which indices, what exclusions, how to handle corporate actions, and when to rebalance. Any of those decisions can have real‑world consequences for counterparties and for perceptions of central‑bank neutrality.

What if the tide turns?

The same AI‑powered rally that lifted the SNB’s top names has also injected volatility. Concentration risk is no longer theoretical when five companies can swing global indices in a single session. A sharp correction in Big Tech would not change the SNB’s mandate, but it could translate into sizable accounting losses and complicate distributions to cantonal governments, which in recent years have become accustomed to dividends from the central bank’s past profits. Officials say monetary policy decisions are insulated from mark‑to‑market swings—yet the politics rarely are.

Liquidity and market impact

To its credit, the SNB chose the deepest pond. U.S. mega‑caps are among the most liquid securities in the world, which allows the bank to move large sums without distorting prices. Disclosures also suggest the SNB adjusts at the margin—adding to winners as index weights change and trimming others when necessary—rather than trading tactically. Still, with tens of billions in the same few names as every index fund on earth, even mechanical flows can compound market momentum.

What it means for Silicon Valley

For the companies themselves, a central bank among the shareholder ranks is both mundane and remarkable. Mundane because the SNB behaves like a quiet index fund: it does not agitate on proxy ballots or make demands on strategy. Remarkable because the presence of a monetary authority underscores how deeply the macroeconomy and the tech cycle have intertwined. From GPU supply chains to cloud‑AI spending plans, the same forces that set interest rates are now—indirectly—meaningful owners.

The next chapter

The SNB’s latest filing will not be its last big number. As long as the franc remains a refuge and the U.S. market remains the world’s most liquid and innovative, Switzerland’s central bank will have powerful reasons to keep sizable equity exposure abroad. If anything, the politics may tighten before the portfolio does: expect louder calls to formalize risk limits, improve transparency around index choices, and clarify what happens when market cycles turn. For now, though, the snapshot is clear: a conservative institution has become an accidental giant of American tech—and one of the quietest whales in Silicon Valley.

Note: Figures reflect SNB’s Form 13F filings for quarter ended June 30, 2025.