Is the Market Still Overvalued? 5% Cheap, but a Bubble Can Stay 'Cheap' in a Narrow Trade

Morningstar's fair-value gauge still reads below parity, but the rebound has been narrow

Morningstar's US equity universe is still trading at a 5% discount to fair value. Its price/fair-value gauge fell to 0.88 at the end of March and then recovered to 0.95 by the end of April. That suggests the market is not in obvious bubble territory, but it also does not look especially safe.

That distinction matters. A market can look modestly cheap on a broad measure and still be driven by a very narrow set of winners.

Why the rally has felt so one-dimensional

Morningstar's valuation metric is built from the median price/fair value of constituent companies, so it is not the same thing as a single multiple flashing on a screen. Even so, the recent upside has come from a small group. From late March to late May, nine of the top 10 contributors to market returns were tied to AI, and they accounted for two-thirds of total market return.

That helps explain why the bull case has felt so loud even while the overall fair-value reading remains below parity.

Why concentration still matters

April leadership was highly concentrated in AI and mega-cap winners. As that leadership narrowed, the margin of safety implied by the broad fair-value measure became less comforting. If a small group of stocks keeps doing most of the work, the market can still feel fragile even when the headline valuation number is not screaming bubble.

The bear case is less about one "cheap" metric than about concentration and stretched expectations

The bear case is not simply that one valuation screen says the market is expensive. It is that the market may be structured like a concentration trade, where sentiment can unwind before fundamentals fully catch up.

High valuation readings leave less room for error

Bears point to several indicators that all look stretched at once. The Buffett Indicator hit 233.8%. The S&P 500's P/E reached 25.5, and the Shiller CAPE Ratio climbed to 40.43. None of those readings alone proves a correction is imminent, but together they suggest limited room for error if expectations wobble.

High valuations do not automatically trigger a crash. What they usually imply is that future returns may be more limited than they would be at more normal levels.

S&P 500 returns now depend heavily on a small group of names

Concentration is the other reason caution still matters. The top 20 companies account for 49% of the index and delivered 64% of its five-year return. That means a disproportionate share of "the market's" performance depends on a relatively small group of mega-caps staying dominant.

That concentration is not purely sentimental. AI infrastructure spending is estimated at $725 billion in 2026, which helps explain why the leaders have had real revenue and capex support behind the story. The risk is not that the narrative lacks fuel; it is that the market may still be too dependent on a narrow AI-led winners' circle.

The practical takeaway is balance, not ideology

The market is still slightly below fair value, but the gap between growth and value has narrowed. That argues against treating growth as an automatic winner or value as a default safe harbor.

A more measured posture is a barbell: keep enough growth exposure to participate if AI leadership broadens, while retaining value exposure in case rotation slows the concentration trade. The goal is not to call a top. It is to avoid assuming that today's index return is still as diversified as it once was.

Why plain cap-weighted indexing is less obvious here

The S&P 500 has become a tech- and AI-dominated index. That does not mean investors should abandon broad equity exposure. It does mean that a blind buy-and-hold approach can still leave you heavily exposed to the same narrative trade, even if it feels diversifying.

If you want more upside to mega-cap or AI leadership, you can own that deliberately. But you do not need to confuse a top-heavy benchmark with broad, risk-spread market exposure.

What to watch next

• Whether leadership broadens beyond the current AI-heavy winners
• Whether growth and value continue to trade at similar discounts to fair value
• Whether mega-cap concentration starts to ease or remain elevated
• Whether AI spending and earnings support keep spreading to a wider set of companies

If leadership broadens while valuations stay reasonable, the rally would look healthier. If concentration deepens without a similar improvement in breadth, caution remains the more disciplined stance.