Nasdaq 15,000 is near. Do I hear 30,000?

To be sure, the Nasdaq Composite is artificially high because of its artificially low levels in the early days of the coronavirus pandemic. But that explains only part of how quickly the Nasdaq could hit 30,000. If we instead extrapolate the Nasdaq’s return over the past five years, it only marginally increases how long it will take for it to do so — to 3.3 years.

A related parlor game is to imagine how long it will take for the Nasdaq index to eclipse the Dow Jones Industrial Average DJIA, +0.24%. That would take somewhat longer, since the Dow itself would rise as the Nasdaq tries to overtake it. But, assuming these two benchmarks’ respective five-year growth rates persist, the Nasdaq would overtake the Dow in 9.9 years — in the summer of 2031.

Here’s the catch

Before you get too excited by the prospect of these lofty Nasdaq Composite levels, you should know there’s a catch: These projections depend crucially on the time period you choose to extrapolate into the future. Not all lead to rosy projections.

For example, instead of focusing on the last one- or five-year periods, use the past 21+ year period to extrapolate. That takes you back to the top of the internet bubble, right before the Nasdaq Composite shed almost 80% of its value as that bubble deflated. Assuming the Nasdaq’s growth rate since the March 2000 top, it would hit the 30,000 mark in 14 years and never overtake the Dow — since these blue-chip stocks in fact have outperformed the Nasdaq over the past 21+ years.

So the real point of these parlor games should be to introduce a reality check into your projections of the market’s future. Recent years have been far better for equities than we have any right to expect going forward.

What is realistic? The answer depends on various factors, such as whether you take the market’s current extreme overvaluation into account. But if you simply extrapolate the past into the future without regard to valuation, you should look at as long a past as possible. In the case of the U.S. market, data is available at least as far back as 1793 (courtesy of a database from Edward McQuarrie, professor emeritus at the Leavey School of Business at Santa Clara University).

Based on his database, here’s what I project for the Nasdaq’s performance in coming years:

• Overall market’s annualized return since 1793: 6.1% annualized above inflation
• Expected inflation over next decade: 1.6% (per Cleveland Fed model)
• Nasdaq Composite’s expected return relative to overall market: Minus 0.1% annualized (per data since 1926 from Dartmouth professor Ken French on the performance of the large-cap growth sector, which is closest to the stocks that dominate the Nasdaq Composite)

The net result: A nominal return of 7.6% annualized in future years. That’s a lot lower than the Nasdaq Composite’s 41.8% return over the past 12 months, or its 23.8% annualized return over the past five years.

In fact, 7.6% annualized is not much better than the Nasdaq Composite’s average return since the top of the internet bubble. At a 7.6% annualized clip, it will take 9.7 years for the index to reach 30,000. Keep in mind that, assuming that the market’s current overvaluation impacts equities’ future return, it will take even longer for the Nasdaq Composite index to reach 30,000.

The bottom line? Trees don’t grow to the sky. While celebrating the good fortune the markets have produced in recent years, most definitely you should not get greedy.

Mark Hulbert is a regular contributor to MarketWatch. His Hulbert Ratings tracks investment newsletters that pay a flat fee to be audited. He can be reached at [email protected]

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