U.S. wealth has shifted to stocks from homes. There are big reasons to worry.

The composition of U.S. household wealth has changed notably: equities now represent a larger share of assets than residential real estate. That shift reflects a four-year bull market in stocks, with the AI boom acting as a major driver of recent gains. When equity values rise faster than home values, portfolios become more sensitive to market moves.

There is a second, less discussed channel. A sustained rally can raise the cost of money. Stronger asset prices and buoyant demand can keep borrowing conditions tighter than they would otherwise be, which matters for households carrying debt and for businesses planning investment. In other words, the same market strength that lifts wealth can also make financing more expensive.

What to watch: whether equity gains stay broad or narrow to AI-linked names, how home prices and mortgage rates evolve alongside stocks, and whether households treat paper gains as spendable wealth. Concentration cuts both ways — it amplifies gains, but it can also amplify the impact of a reversal on consumer confidence and spending.