When Do High P/E Ratios Make Sense?

A High P/E Is Not Automatically a Warning

A company-level look at this question already lives on the site. This piece asks the same question about a whole market.

"The Nifty is at 22 times earnings, higher than its peers, so it must be expensive." The instinct is common. It can be right, but it is not proof. A market's P/E is a price for a stream of future profits, and the fair price depends on what that stream looks like.

The Market P/E in One Formula

Treat the market as one large company that pays out part of its profit and reinvests the rest. A simple model gives a "justified" P/E on next year's earnings:

Justified P/E = (1 - g ÷ ROE) ÷ (r - g)

• r is the cost of equity, the return investors require.
• g is the long-run growth rate of earnings.
• ROE is the return companies earn on the equity they reinvest. The term (1 - g ÷ ROE) is the share of profit that does not need to be reinvested to grow at g.

Three things push a justified P/E up: a lower cost of equity, higher long-run growth and higher returns on reinvested capital. P/E ratio basics are in The Vault.

A Worked Example: Justified P/E for an Index

Illustrative example. Assume companies earn an 18% ROE on reinvested capital.

Two things stand out. First, a P/E in the low 20s can be fully justified, for example with 10% long-run growth and a 12% cost of equity. Second, the answer is extremely sensitive. A one-point change in either input can move the justified P/E by a third or more.

Return on equity matters too. With 9% growth and a 12% cost of equity, the justified P/E is 13.3 at an ROE of 15%, 16.7 at 18% and 21.3 at 25%. A market full of high-return companies deserves a higher multiple than one full of low-return companies growing at the same pace.

Reverse the Question

Instead of asking whether a P/E of 22 is too high, ask what it requires. Using the same formula with an 18% ROE:

• At a 12% cost of equity, a P/E of 22 implies earnings growth of about 10% a year, forever.
• At a 13% cost of equity, it implies about 11.3% a year, forever.

Now the question is concrete. Can Indian corporate earnings grow at 10% to 11% a year, on average, for decades? Nominal GDP growth in India has often been in that range or higher, so the answer is not obviously no. But it leaves little room for error. If the cost of equity rises, or growth slows, the same P/E stops being supported.

This is why interest rates matter so much for market valuation. When bond yields rise, as they did in many countries in 2026, investors demand a higher return from shares too. The growth needed to justify the same P/E rises with it.

Conditions That Support a High Market P/E

• Low or falling interest rates, which lower the cost of equity.
• Long, reliable nominal growth. Higher nominal GDP growth supports higher long-run earnings growth, which is part of the usual case for India's premium.
• High returns on capital, so growth needs less reinvestment.
• Temporarily depressed earnings. If profits are cyclically low, the P/E looks high on today's earnings but normal on recovered earnings.

Conditions That Do Not

• Peak margins. A high P/E on record-high profits combines two optimistic bets.
• Rising interest rates. A higher cost of equity pulls the justified P/E down even if growth holds.
• Growth assumptions above the economy's. Over long periods, total corporate earnings cannot grow much faster than nominal GDP.
• A multiple held up mainly by flows, rather than by growth or returns.

2026 showed how quickly these conditions can shift together. Crude oil prices surged, US bond yields climbed, and in October the RBI raised its policy rate for the first time since 2023. A market P/E that looked reasonable in January faced a higher cost of equity and a weaker growth outlook within months. Nothing about the formula changed. Its inputs did.

Traps in Reading Index P/E

• Changes in the earnings basis. From March 2021, NSE moved the Nifty P/E from standalone to consolidated earnings, which lowered the reported figure. P/E readings from before and after are not directly comparable.
• Trailing vs forward. Trailing P/E uses the last twelve months of profit. Forward P/E uses analyst estimates, which are often too optimistic.
• Sector mix. When an index adds more high-P/E sectors, such as consumer companies, its average P/E rises without any single stock becoming more expensive.
• Losses inside the index. Index P/E divides total market value by total earnings. A large loss at one constituent cuts total earnings and pushes the index P/E up, even if every other company is unchanged.
• Comparing with other countries. Different markets have different sector mixes, growth rates and interest rates.

Habits for Judging Market Valuation

1. Write down the r, g and ROE that the current P/E implies, and judge whether they are realistic.
2. Compare P/E with interest rates, not just with its own history.
3. Check where earnings are in the cycle.
4. Use a consistent earnings basis for historical comparisons.
5. Use ranges, given how sensitive the answer is.

The Reframe

A high market P/E is a claim about the future: that rates stay low enough, growth stays long enough and returns stay high enough. The question is never whether the P/E is high. It is whether that claim is believable.