Financial markets have become increasingly agitated about whether investors chase the parabolic rise in artificial intelligence stocks and bet on AI adoption more broadly, or hedge fears of a prolonged inflation burst due to lax money and fiscal policies worldwide.

Right now they appear to be betting on both, with tech-heavy stock indexes hitting records in tandem with soaring gold. Global equities are up 17 percent in 2025 while gold has gained 50 percent.

Business consultants McKinsey put some shape on the bigger picture with its updated release this week on what it calls the "global balance sheet" of GDP, savings and debt.

The top-line metrics from this "state of the world" number crunch are eye-catching.

Global net worth in aggregate has nearly quadrupled since 2000 to $600 trillion at the end of last year and will have climbed further given the market moves of the past nine months.

But this is getting further and further from underlying economic performance, moving from 4.7 times world GDP 25 years ago to 5.4 times now. And the concentration of that wealth remains alarming, with just 1 percent of people owning a fifth of it.

By devaluing assets and debt in real terms, the post-pandemic inflation burst kept something of a lid on this outsize expansion but we appear to have reached another juncture.

"When the balance sheet outruns the underlying economy, it exposes weaknesses," the McKinsey Global Institute (MGI) said.

"When real estate and equity values rise faster than GDP, capital may disproportionately go to asset repurchases, sometimes with a lot of leverage," the MGI authors wrote. "This pushes up valuations further but leaves the economy deprived of the type of investment that generates long-run growth."

More than a third of the $400 trillion rise in wealth since the turn of the century was essentially just paper gains, decoupled from the real economy, and about 40 percent was cumulative inflation, McKinsey added.

That means only 30 percent reflected new investment in the real economy or, put another way, every dollar of new investment created $3.50 of new household wealth.

The nature of that kind of asset wealth, whether predominantly equity in the United States or real estate in Europe or deposits in China, can then be inherently unstable, with sizable feedback loops to the real economy in volatile times.

In the US, for example, the market value of corporate equity excluding its debt is almost twice the assets owned by the firms.

But rising wealth effects encourage exuberant behavior, shown in part by the fact that while each dollar of investment created more than three times the amount in wealth, it also created almost $2 of new debt. So much so that global debt is near all-time highs at some 2.6 times global GDP.

The question raised is whether these wealth multiples are sustainable for much longer and what might bring them back closer to the real world.

A market shock, or bubble burst, as many might see it, might help a balance sheet reset, but at the risk of hitting GDP, and all the recession risk and household distress that goes with it.

McKinsey sketched out the two most likely scenarios.

One is an extremely benign view of a productivity boom, perhaps sown by the quantum leap in AI now unfolding that allows growth to catch up, stock values to stay strong without overheating wages and prices. There is less of a reset but a more sustainable underpinning.

The less favorable outcome is one of prolonged high inflation, which could help erode nominal debts but with toxic fallout for poorer households, business planning, the wider economy and political stability.

"Economies are unlikely to achieve balance while preserving wealth and growth unless productivity accelerates," MGI said. "Other scenarios sacrifice one or the other or both."

Regionally, of course, the numbers break down differently and cross-border imbalances have grown.

But for the average US saver the difference between the two most likely scenarios could amount to as much $160,000 by 2033. A productivity boost that lifts annual GDP growth by more than one percentage point above trend could lift per capita US wealth by $65,000 over that period, while sustained inflation could eat into net worth to the tune of $95,000.

Market tensions already show investors are testing both scenarios and building portfolios to protect them in the event that either unfolds. Tense times indeed.

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The writer is a columnist for Reuters. The views expressed are personal.