Jeremy Grantham: The AI investment boom risks overvaluation, historical bubbles provide crucial insights, and value investing’s cyclical nature remains vital | Capital Allocators

AI investment surge risks echoing past bubbles, highlighting the importance of understanding historical market trends.

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Add us on Google by Editorial Team Mar. 23, 2026

Key takeaways

• The current AI investment boom may mirror past market bubbles in its potential overvaluation.
• Transformative ideas often lead to investment bubbles, as seen with railroads and the internet.
• Quantitative models can create portfolios that closely resemble those selected by experts.
• Value investing has historically outperformed growth investing, despite periodic downturns.
• Investment managers face significant pressure to perform during bull markets, often leading to job loss.
• Managers are more likely to be fired for underperformance in bull markets than in bear markets.
• Large companies should adapt to bull markets rather than resist them for better business outcomes.
• Grantham’s funds outperformed the market during the bear market of the early 2000s.
• The housing market bubble of 2002-2006 was larger than any US stock market bubble.
• Historically, all bubbles have reverted to their pre-bubble trends.
• Understanding past market bubbles can provide insights into current investment trends.
• Quantitative investing can complement traditional stock selection methods effectively.
• The cyclical nature of investment strategies is crucial for navigating market dynamics.
• Market pressures during bull markets can lead to rapid career changes for investment managers.
• Adapting to market cycles is essential for large companies to maintain business success.

Guest intro

Jeremy Grantham is Co-Founder and Chief Investment Strategist of GMO, a Boston-based asset management firm. He co-founded Batterymarch Financial Management in 1969 and recommended commercial indexing in 1971, one of the earliest such efforts. Over six decades, he has been a leading voice on value investing, market bubbles, and long-term strategy.

The AI investment boom: A bubble in the making?

• The current AI investment boom is compared to past bubbles, suggesting potential overvaluation.

• Here we are with nvidia looking like amazon… the investment program is almost certain to be overdone.

  — Jeremy Grantham

• Historical bubbles often involve significant ideas that become overhyped, such as railroads and the internet.

• The great bubbles are associated with great investment ideas that get overdone… railroads are the best example followed by the internet.

  — Jeremy Grantham

• Understanding the characteristics of past bubbles can help identify similar patterns in AI investments.
• The AI boom is driven by transformative technology, paralleling past investment trends.
• Excessive investment in AI may lead to a market correction similar to previous bubbles.
• Investors should be cautious of overhyped sectors that resemble historical bubble patterns.

The role of quantitative models in investment

• Quantitative models can create portfolios similar to those selected by experts.

• We got it to kick out a portfolio which was 90% the same as ours interestingly the 10% that was different did just as well as our 10%.

  — Jeremy Grantham

• Combining quantitative models with expert judgment can enhance stock selection.
• Quantitative investing offers a systematic approach to portfolio management.
• The evolution of quantitative models has transformed traditional investment strategies.
• Quantitative models can provide consistency and objectivity in investment decisions.
• The integration of quantitative methods can improve investment performance.
• Quantitative models are valuable tools for navigating complex market dynamics.

Value vs. growth investing: A historical perspective

• Value investing has historically outperformed growth investing but experiences downturns.

• Value had won for eighty years or so but it only won two out of three years every now and then there’d be a two or three year interval where it would do very badly and then it would surge back.

  — Jeremy Grantham

• Understanding the historical performance of value and growth strategies is crucial for investors.
• Value investing’s cyclical nature requires patience and long-term perspective.
• Growth investing may outperform during certain market conditions, challenging value strategies.
• Historical trends in value and growth investing provide insights into future market behavior.
• Investors should consider both value and growth strategies for diversified portfolios.
• Recognizing the cyclical patterns of investment strategies can inform better decision-making.

The pressures of investment management in bull markets

• Investment managers face severe consequences for underperformance during bull markets.

• In the great internet bull market people were so excited so much money was being made by their competing pension fund officers… they would fire you very quickly.

  — Jeremy Grantham

• Managers are often fired for underperformance in bull markets rather than bear markets.

• People think you get fired for underperforming in bear markets which is nonsense… in the great internet bull market people were so excited… they would fire you very quickly.

  — Jeremy Grantham

• The competitive pressures of bull markets can lead to rapid career changes for managers.
• Understanding market dynamics is essential for managing investment performance expectations.
• Bull markets create unique challenges for investment managers to navigate.
• The psychological impact of peer performance can influence investment decisions.

Adapting to market cycles: A strategy for large companies

• Fighting against a major bull market is a poor business strategy for large companies.

• The meta message is if you’re a big company you can’t fight a major bull market it’s ridiculous it’s terrible business you have to roll with the punch try and be more persuasive on the way down and up and get back in quicker get out faster on the way down just execute and talk a good game and you will not be in any serious danger.

  — Jeremy Grantham

• Large companies should adapt to market cycles to maintain business success.
• Adapting to bull markets can prevent significant business risks for large companies.
• Understanding market cycles is crucial for strategic decision-making in large organizations.
• Companies should focus on adaptability and resilience during market fluctuations.
• Effective market strategies involve recognizing and responding to market trends.
• Large companies can benefit from aligning business strategies with market cycles.

Grantham’s funds: Outperformance during bear markets

• During the bear market, Grantham’s funds achieved significant outperformance.

• We actually made nice money in 2000 nice money in 2001 and hung in by half a percent in 2002 which was minus 22% the third year of a bear market and the s and p was down 22% now we’re serious we were not down we were up nicely even our asset base with people still leaving on a lagging basis our assets went up from 20,000,000,000 to 22,000,000,000.

  — Jeremy Grantham

• Grantham’s expertise in investment strategy led to successful performance during downturns.
• Understanding market dynamics can lead to outperformance in challenging conditions.
• Grantham’s approach highlights the importance of strategic asset management.
• Successful investment strategies can maintain asset growth during market downturns.
• Grantham’s funds demonstrate the potential for positive returns in bear markets.
• Effective investment strategies involve adapting to market conditions for sustained success.

The housing market bubble: A statistical anomaly

• The housing market bubble of 2002-2006 was larger than any US stock market bubble.

• My favorite bubble was the housing market the housing market was a bigger bubble statistically than any stock market bubble in america.

  — Jeremy Grantham

• Understanding the historical context of housing market trends is crucial for investors.
• The housing market bubble provides insights into market dynamics and investment risks.
• Comparing housing and stock market bubbles highlights unique investment challenges.
• The housing bubble’s size and impact underscore the need for careful market analysis.
• Recognizing the signs of a bubble can inform better investment decisions.
• The housing market bubble serves as a case study for understanding market anomalies.

The inevitability of bubble reversion

• Every bubble historically has returned to its pre-bubble trend.

• We found that every bubble had broken… there was no exception to the principle that an overpriced market at two sigma… all of them went back to the trend that existed prior to the bubble.

  — Jeremy Grantham

• Understanding bubble reversion is critical for assessing investment risks.
• Historical bubble behavior provides insights into future market corrections.
• The principle of bubble reversion highlights the importance of market trend analysis.
• Recognizing the inevitability of reversion can guide investment strategies.
• Bubble reversion serves as a reminder of the cyclical nature of markets.
• Investors should be aware of the historical patterns of bubble reversion for better decision-making.

Disclosure: This article was edited by Editorial Team. For more information on how we create and review content, see our Editorial Policy.