
Harry Mamaysky
· Professor of Professional Practice in the Faculty of BusinessVerifiedColumbia University · French and Italian
Active 1999–2026
Research topics
- Computer Science
- Business
- Economics
- Finance
- Internal medicine
- Microeconomics
- Econometrics
- Financial economics
- Financial system
- Physics
- Astrophysics
- Medicine
- Virology
Selected publications
SSRN Electronic Journal · 2026-01-01
preprintOpen access1st authorCorrespondingBig Data Meets the Turbulent Oil Market
Financial Analysts Journal · 2026-01-02
articleSenior authorCredit Information in Earnings Calls
SSRN Electronic Journal · 2025-01-01 · 1 citations
preprintOpen accessFactor Model Selection Using the ICAPM
SSRN Electronic Journal · 2025-01-01
preprintOpen access1st authorCorrespondingDoes Overnight News Explain Overnight Returns?
ArXiv.org · 2025-07-06
articleOpen accessSenior authorOver the past 30 years, nearly all the gains in the U.S. stock market have been earned overnight, while average intraday returns have been negative or flat. We find that a large part of this effect can be explained through features of intraday and overnight news. Our analysis uses a collection of 2.4 million news articles. We apply a novel technique for supervised topic analysis that selects news topics based on their ability to explain contemporaneous market returns. We find that time variation in the prevalence of news topics and differences in the responses to news topics both contribute to the difference in intraday and overnight returns. In out-of-sample tests, our approach forecasts which stocks will do particularly well overnight and particularly poorly intraday. Our approach also helps explain patterns of continuation and reversal in intraday and overnight returns. We contrast the effect of news with other mechanisms proposed in the literature to explain overnight returns.
Does Overnight News Explain Overnight Returns?
SSRN Electronic Journal · 2025-01-01
preprintOpen accessSenior authorTime Variation in the News–Returns Relationship—ERRATUM
Journal of Financial and Quantitative Analysis · 2024-10-04
erratumOpen accessSenior authorarXiv (Cornell University) · 2023-09-11
preprintOpen accessAn increase in the novelty of news predicts negative stock market returns and negative macroeconomic outcomes over the next year. We quantify news novelty - changes in the distribution of news text - through an entropy measure, calculated using a recurrent neural network applied to a large news corpus. Entropy is a better out-of-sample predictor of market returns than a collection of standard measures. Cross-sectional entropy exposure carries a negative risk premium, suggesting that assets that positively covary with entropy hedge the aggregate risk associated with shifting news language. Entropy risk cannot be explained by existing long-short factors.
News and Markets in the Time of COVID-19
Journal of Financial and Quantitative Analysis · 2023-10-31 · 13 citations
articleOpen access1st authorCorrespondingAbstract The onset of COVID-19 was characterized by voluminous, negative news. Higher narrativity news topics (measured by textual proximity to articles describing the 1987 stock market crash and textual distance from Federal Reserve communications) were systematically associated with contemporaneous market responses, which were larger on high volatility days (hypersensitivity), and with markets–news feedback. Hypersensitive news topic-market pairs were associated with next-day reversals. A test using the news–markets relationship identifies a mid-March 2020 structural break, which was knowable by the end of April. Post break, markets and news became considerably less coupled, and hypersensitivity and reversals abated.
Time Variation in the News–Returns Relationship
Journal of Financial and Quantitative Analysis · 2023 · 13 citations
Senior authorCorresponding- Econometrics
- Economics
- Physics
Abstract The speed of stock price reaction to news exhibits substantial time variation. Higher risk-bearing capacity of financial intermediaries, lower passive ownership of stocks, and more informative news increase price responses to contemporaneous news; surprisingly, these interaction variables also increase price responses to lagged news (underreaction). A simple model with limited attention and three investor types (institutional, noninstitutional, and passive) predicts the observed variation in news responses. A long–short trading strategy based on news sentiment earns high returns, which increase when conditioning on the interaction variables. The interactions we document are robust to the choice of news source.
Frequent coauthors
- 56 shared
Charles W. Calomiris
Utah State University
- 18 shared
Paul Glasserman
Columbia University
- 9 shared
Andrew W. Lo
- 6 shared
Matthew Spiegel
Yale University
- 6 shared
Yiwen Shen
Tianjin University of Technology and Education
- 5 shared
Nida Çakır Melek
- 5 shared
Hua He
Sichuan University
- 4 shared
Jiang Wang
Taiyuan University of Technology
Education
- 2000
PhD, Finance
Massachusetts Institute of Technology Sloan School of Management
- Resume-aware match score
- Save to shortlist
- AI-drafted outreach
See your match with Harry Mamaysky
PhdFit ranks faculty by your research interests, methods, and publications — grounded in their actual work, not templates.
- Free to start
- No credit card
- 30-second signup