Abby Joseph Cohen - Blending the Quantitative with the Qualitative

Episode Summary

Executive Summary: Michael Mebison and Tano Santos interview Abby Joseph Cohen about how quantitative models, market structure, and macroeconomic regimes shape investing. Cohen argues she is a “reformed quant”: models are useful but fail when regimes shift, data are revised, or many investors crowd into the same signal. She emphasizes valuation discipline, warns about bubbles, and highlights globalization, policy, immigration, energy transition, and political misinformation as major forces.

Main Topics: Quantitative models and their limits (Priority: 5/5): Cohen explains how econometric and valuation models are valuable starting points, but can break when economic structure changes, inflation surprises, data are revised, or markets become crowded with the same strategies. Crowding, correlation, and market fragility (Priority: 5/5): The conversation discusses how widespread use of identical models can amplify volatility, with examples like portfolio insurance and the quant crash, turning models from stabilizers into accelerants. Interest rates, valuation, and market regime shifts (Priority: 5/5): Cohen links the multi-decade decline in interest rates to rising equity valuations, leverage, and the growth of private equity, while noting that the regime is now reversing. Indexing, ETFs, and concentration risk (Priority: 4/5): She argues index funds and ETFs helped retail investors, but cap-weighted benchmarks became highly concentrated in a few large stocks, making equal-weight approaches more attractive during the 2022 correction. Crisis, policy response, and central bank evolution (Priority: 4/5): The discussion covers repeated financial crises, COVID, Ukraine, and the expanded role of central banks in stabilization through swap lines, repo facilities, QE, and now tightening. Globalization, supply chains, and reserve currencies (Priority: 4/5): Cohen says globalization is adjusting rather than ending, with more reshoring/nearshoring, more thoughtful supply-chain design, and continued dominance of the U.S. dollar over basket-currency alternatives. ESG, energy transition, and productivity measurement (Priority: 3/5): She stresses realism in the energy transition, notes that carbon producers are funding alternative-energy R&D, and argues productivity is undermeasured in a service-heavy economy.

Key Arguments: Models should be used as tools, but the first question must be why they might fail under a new regime. Market structure matters: when many investors use the same model, herd behavior can create self-reinforcing selloffs or bubbles. The long decline in rates boosted valuations, leverage, private equity returns, and risk-taking; that era is ending. Cap-weighted indices can become dangerously concentrated; equal-weight exposure can outperform when the mega-cap leaders fall. Many “loss-making” companies are not comparable: some are truly unprofitable, while others are making intangible investments that depress current earnings but may create future value. The current environment is closer to a reasonable or pessimistic valuation setup than the euphoric peaks of 1999-2000. Financial crises recur because of valuation excess, policy errors, shocks, and reflexive market behavior. The Fed has expanded beyond interest-rate policy into broader financial-stability operations, which investors should treat as a key part of the policy toolkit. Globalization is not disappearing, but supply chains are being redesigned to add resilience and reduce overdependence. Productivity statistics may understate true growth because service-sector output is hard to measure, especially in finance and other intangibles-heavy industries. Cohen views immigration as a major U.S. growth advantage, contributing materially to labor-force expansion and high-skilled innovation. Her biggest concern is the rise of anti-truth politics, misinformation, and declining respect for science and facts.

Data Points: Time period at Goldman Sachs: 1990 - Cohen joined Goldman Sachs in 1990 and later became chief U.S. portfolio strategist. Managing director promotion: 1996 - She was named a managing director at Goldman Sachs. Goldman partnership: 1998 - She became part of the firm’s partnership shortly before Goldman went public. U.S. labor force growth from immigration: 60% - Cohen said immigrants accounted for 60% of the increase in the U.S. labor force over the last 10 years. PhDs in engineering and applied science who are immigrants: 60-65% - She cited immigrant participation among U.S.-working PhDs in technical fields. NASDAQ decline: 30% - Cohen said the NASDAQ had fallen 30% by mid-May in the 2022 selloff. Largest PE gap in S&P 500: Wider than at any time before beginning of 2022 - She argued valuation dispersion within the index had become historically extreme. IBM revenue hypothetical: 85% of GDP - She said IBM valuation in the 1970s would have required revenues equal to 85% of GDP to be sustained over 20 years. Course duration: Almost a decade - Cohen said she has taught the Columbia course with Pierre Yared for nearly ten years. Public-sector productivity assumption in finance: Zero - She noted that government data once effectively assigned zero productivity growth to parts of the FIRE sector due to measurement limits.

Pivotal Quotes: "I used to be a quant. I am a reformed quant." — Abby Joseph Cohen: She summarizes her philosophy on using models: start quantitatively, but recognize when structural change breaks the model. "The Fed and other central banks have recognized over the last two decades in particular that they have policy tools that are much broader than what they originally thought." — Abby Joseph Cohen: Discussing the evolution of monetary policy beyond traditional interest-rate moves into liquidity facilities and QE. "Trees don't grow to the sky." — Abby Joseph Cohen: She used this line to caution against assuming large technology leaders can grow indefinitely at extraordinary rates.

Implications: Investors should pair models with judgment, expect more regime change, and watch concentration, policy, and valuation carefully. The U.S. still has structural advantages, but misinformation, energy transitions, and supply-chain redesign will shape returns and risks.