Kenneth French
Economist known for the Fama and French factor models
Born 1954
Co-developed models showing that company size and relative valuation help explain long-run differences in stock returns.
Biography
Kenneth French is an American economist, born in 1954, best known for the empirical asset pricing research he conducted with Eugene Fama. Their work established that a single measure of market risk did not explain the pattern of long-run stock returns, and that company size and relative valuation carried explanatory power of their own.
He is the Roth Family Distinguished Professor of Finance at the Tuck School of Business at Dartmouth College. Alongside the research itself, he maintains a widely used public data library of factor returns, which has allowed researchers and practitioners to test claims against a common dataset rather than proprietary ones.
The practical consequence of this work is the factor investing industry: funds that deliberately tilt toward smaller companies or cheaper valuations rather than simply holding the market in proportion to value. French himself has generally been careful about how far the findings should be pushed.
Career timeline
- 1954Born in the United States.
- 1983Completes a PhD in finance at the University of Rochester.
- 1992Publishes "The Cross-Section of Expected Stock Returns" with Eugene Fama.
- 1993Publishes the three-factor model with Eugene Fama.
- 2015Publishes the five-factor asset pricing model with Eugene Fama.
How he approaches the evidence
The Fama and French research programme is empirical before it is theoretical. The method is to look at long histories of returns, identify characteristics that reliably line up with differences in average return, and only then argue about what those characteristics might represent.
That ordering matters for how the results should be read. Establishing that cheaper or smaller companies have historically earned higher average returns does not establish why, and the two main explanations, compensation for risk and persistent mispricing, imply quite different expectations about the future.
Key ideas
Tap any idea to expand a plain-English explanation, why it matters, and where to learn more.
Size and value as explanatory factors
Company size and the ratio of book value to market value help explain differences in average stock returns that a single market factor does not.
It showed the capital asset pricing model was incomplete as a description of what actually happened in the data.
Portfolios sorted on those characteristics showed systematic return differences over long periods.
Factors are characteristics, not predictions
A factor describes a pattern measured in historical returns rather than a guarantee about future ones.
Factor premiums have gone through long stretches of underperformance, which is difficult to sit through if a pattern was mistaken for a rule.
The value premium was weak for an extended period after the mid-2000s.
Shared data raises the standard of evidence
Publishing factor return data openly lets independent researchers test the same claims on the same inputs.
It makes results checkable, which is unusual in a field where much analysis rests on proprietary data.
The Dartmouth data library is a standard reference in academic and practitioner research.
Major contributions
- Co-developed the three-factor asset pricing model with Eugene Fama, adding size and value to the market factor.
- Co-developed the later five-factor model incorporating profitability and investment.
- Maintains a public data library of factor returns used widely in academic and practitioner research.
Important books
- The Cross-Section of Expected Stock Returns1992
A journal article rather than a book, and the paper most often cited as the origin of the modern factor literature. Written with Eugene Fama.
Influence on investors
Factor investing as a product category exists largely because of this research. Funds that tilt toward smaller or cheaper companies are implementing a version of what these papers documented, and the vocabulary of factors and premiums entered practice from here.
Criticisms and debates
A balanced view includes the main criticisms and open debates, presented neutrally.
- Some documented factor premiums have weakened after publication, raising the question of whether they were partly artefacts of the sample period.
- Whether the premiums represent compensation for risk or persistent mispricing remains genuinely unsettled, and the two readings imply different expectations.
- Implementing factor tilts incurs trading costs and tracking difference that academic return series do not include.
Lessons for investors
Plain-English takeaways. Context for learning, not advice to buy or sell anything.
- 1Treat a factor as a description of what happened historically rather than as a promise about what comes next.
- 2Expect long stretches where a documented premium does not appear, because that is what the record shows.
- 3Prefer claims that can be checked against openly available data.
Notable quotes
“Size and value characteristics help explain differences in average stock returns.”
Context: The Fama-French finding that company size and valuation explain returns a single market factor does not.
Frequently asked questions
Who is Kenneth French?
Kenneth French is an American economist born in 1954 and a professor at the Tuck School of Business at Dartmouth College, best known for empirical asset pricing research conducted with Eugene Fama.
What is the Fama-French three-factor model?
A model that explains stock returns using three factors: overall market exposure, company size, and the ratio of book value to market value. It extended earlier single-factor models.
What is the Data Library?
A publicly available dataset of factor returns that French maintains at Dartmouth. It is widely used because it lets different researchers test claims against the same inputs.
Does factor investing still work?
The historical patterns are well documented, but premiums have gone through long periods of underperformance and there is genuine disagreement about whether they reflect risk or mispricing. This is education, not a recommendation.
Related quotes
Other people in the library writing on the same themes.
“It is not from the benevolence of the butcher, the brewer, or the baker that we expect our dinner, but from their regard to their own interest.”
Adam Smith“The long run is a misleading guide to current affairs. In the long run we are all dead.”
John Maynard Keynes“There is no such thing as a free lunch.”
Milton FriedmanStrategies Kenneth French is associated with
How the money actually gets run, with the mechanics, the costs and the failure modes set out in full.
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Educational content only. This is a neutral summary compiled for learning. It is not an endorsement, not investment advice, and not a claim that this person is always right. Mentioning someone here does not imply they are affiliated with Money Masters Media.