Warren Buffett’s favourite market valuation gauge — the market cap-to-GDP ratio — has climbed to over 230%, which is a record level. With US stocks still near all-time highs, the signal is once again raising a familiar question: are investors ignoring a classic warning sign?
Why is the Buffett indicator so high?
The rise in the market cap-to-GDP ratio to over two times is less about a single bubble and more about concentration.
A large part of US equity gains has been driven by a small group of mega-cap technology stocks. The so-called ‘Magnificent 7′ now account for an outsized share of total market value, meaning index-level valuations are heavily skewed by a narrow set of AI-exposed companies.
That concentration reflects a broader narrative shift. Markets are increasingly trading around the AI theme, with semiconductors, cloud infrastructure, and data centre operators absorbing a disproportionate share of capital flows.
However, there are growing questions around whether the pace of investment is running ahead of monetisation. Hyperscalers are committing vast sums to AI infrastructure, but the number of clear ‘killer applications’ remains limited, and the return profile is still uncertain.
At the same time, the physical buildout is becoming more complex. Data centres face constraints around electricity supply, water usage, and local planning approvals. Some US states are actively putting the brakes on further approvals.
Even high-profile speculative listings and pre-IPO hype around companies such as SpaceX sit within this broader environment — not as the driver, but as a reflection of the same risk appetite.
An alternative way to play the AI arms race
If the AI trade is driving extreme market concentration, the obvious question is whether investors need to own the most expensive parts of that ecosystem at all.
One alternative approach is to focus on the physical constraints required to make the AI buildout possible.
Copper sits at the centre of that equation.
It’s essential for power grids, data centres, semiconductors, and electrification more broadly. Yet supply is struggling to keep pace with the scale of demand being implied by the AI investment cycle.
Copper giant
This is where Glencore (LSE: GLEN) becomes relevant.
Over the past year, copper prices have moved higher as structural supply tightness has started to emerge. In response, the miner has signalled plans to expand output through brownfield projects, with production expected to rise materially over the coming decade.
That positions the group to benefit if the current buildout phase continues, particularly if demand from data infrastructure and electrification proves more persistent than existing supply assumptions.
Importantly, this isn’t a short-term pricing story. New copper supply is slow to develop and highly capital intensive. Historically, the industry has struggled to respond quickly enough to sustained demand shocks of this scale.
The key risk is timing — both in terms of how durable AI-related demand proves to be, and how quickly new supply can realistically come online.
But if the AI narrative ultimately comes down to compute capacity and physical infrastructure, then copper is one of its most critical constraints. Glencore offers exposure not to the hype around AI itself, but to the industrial inputs required to make it happen. That’s why I view it as one to consider.
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Andrew Mackie owns shares in Glencore.
