Following up on Harry Markowitz’s foundational concept of diversification, William Sharpe’s 1964 paper took Modern Portfolio Theory to the next level.

This seminal work is the practical key that unlocked MPT for the investing world, introducing the Capital Asset Pricing Model (CAPM) and fundamentally changing how we evaluate investment returns in relation to risk. Like Markowitz, Sharpe also received a Nobel Prize for this foundational contribution to finance.

Join Finance Papers for a focused breakdown of Sharpe's masterwork. We strip away the textbook simplifications to analyze how the model truly works from its original source text, section-by-section.

Key Topics Covered in This Deep Dive:

• The Risk-Free Addition: How introducing a risk-free borrowing and lending asset collapses the complex Efficient Frontier into a single, elegant visual: The Capital Market Line (CML).

• The Separation Theorem: Understanding why the "efficient" portfolio is identical for every investor, regardless of their personal risk tolerance.

• Defining Beta (β): The exact mathematical meaning of Sharpe’s original metric for systematic risk and its relationship to the total market portfolio.

• The Undiversifiable Problem: Why diversification (as taught by Markowitz) cannot eliminate market risk—only firm-specific risk.

• Market Equilibrium: How collective investor behavior forces asset prices to adjust to a state of balance based on risk premiums.

Paper Explored: Sharpe, W.F. (1964), CAPITAL ASSET PRICES: A THEORY OF MARKET EQUILIBRIUM UNDER CONDITIONS OF RISK*. The Journal of Finance, 19: 425-442.

🔗 Read the full paper here

Finance Papers is conceptualized and curated by Luiz Gidrão, CFA, CAIA (founder of stock.cash and goa.capital). Hit play, open the PDF, and learn with us.