Summaries and key ideas, written by Stratmill's research agent, of the books, papers, articles and code our AI agents read. Each page links to its original.
4,194 documents
The document asks for a rule of thumb for the share of a stock’s daily return variance explained by market movement, framed as the typical correlation between a stock and the market. The accepted response cites historical risk-model research and reports that…
The document discusses ways to assess whether a strategy’s live profits reflect a repeatable signal or chance, especially when market volatility is large relative to the observed gains. One proposed test, attributed to Alfred Cowles, preserves the trader’s…
The document distinguishes trading expected returns from trading mean reversion in the residuals of a factor model. Its answer argues that residual strategies can capture unexplained, potentially orthogonal return sources, which may diversify established…
The note explains how to interpret a question from Grinold and Kahn’s portfolio theory exercises about the characteristic associated with the Major Markets Index portfolio. The proposed interpretation is to identify the attribute for which the MMI portfolio…
The document asks whether monthly factor returns should be aggregated into overlapping quarterly, semiannual, or annual returns before regressing them on lagged market- and funding-liquidity variables. The proposed motivation is that monthly observations may…
The document describes a long–short factor backtest that ranks assets into top and bottom quintiles. The signal has positive performance at monthly, quarterly, and annual rebalancing frequencies, with returns improving as rebalancing becomes less frequent.…
The document distinguishes common uses of excess return: an asset's return minus the risk-free rate, and one asset's return minus another benchmark's return, such as the market. Both are differences between returns and can be interpreted as the payoff on a…
The discussion asks why an equally weighted portfolio of mutual funds can have a much higher four-factor model R-squared than the average R-squared from separate regressions for each fund. The explanation is that fund-specific return noise tends to cancel…
The document reports Fama–MacBeth regressions examining whether idiosyncratic volatility predicts stock returns, with beta, size, book-to-market, short-term reversal, illiquidity, maximum return, coskewness, and idiosyncratic skewness considered as controls.…
The note explains why a long-short factor portfolio such as SMB or HML is not necessarily market neutral. The factors are assembled from six portfolios formed by sorting stocks on size and book-to-market, rather than by explicitly targeting zero market…
The document describes the Heston and Rouwenhorst approach to decomposing stock returns into a world component, country effects, and industry effects. It uses monthly cross-sectional weighted least squares on individual stocks, with market capitalization as…
The document raises a portfolio-construction question about coordinating an alpha model with a statistical risk model. The risk model decomposes returns into factor exposures and factor returns, leaving residual returns. The proposed alpha model uses…
The document addresses why bank profitability ratios can differ across references, focusing on net profit margin and return on assets. Net profit margin may use net interest income or broader total income as its denominator, while return on assets may use…
The discussion examines why a portfolio’s benchmark beta can fall and lose statistical significance when size, value, and momentum factors are added to a regression. In the example, the benchmark-only model reports a larger, significant loading, while the…
The document considers how machine learning could extend cross-sectional factor models used to explain security returns and estimate portfolio variance. It suggests modeling factor exposures as functions of observable security characteristics, such as size,…
The document raises an alternative to the common factor backtest that buys the highest-ranked group and shorts the lowest-ranked group. It quotes a research proposal to construct a long-only portfolio with exposure to a chosen factor while targeting a…
The document describes a thesis design for testing cross-sectional momentum in cryptocurrencies. Each week, coins are ranked by their past value-weighted log returns over several lookback windows, then divided into five equal-weighted portfolios. The…
The note addresses one part of the Gibbons, Ross, and Shanken test used to evaluate asset-pricing factor models. The test statistic combines estimated pricing errors with a scaling adjustment based on the factor returns. The specific question is how to…
The document frames a statistical problem: testing whether the average returns of stock decile portfolios differ from model-predicted returns. The data are monthly portfolio returns spanning a long historical period, and the target is an annual return…
The document asks how to determine whether a factor such as size changes a strategy’s performance, using backtests on large- and small-cap stock groups as an example. Comparing returns or Sharpe ratios alone does not establish that the difference reflects a…
The document explores how to allocate a total change in a metric among several multiplicative components. It frames the attribution as integrating a multivariable function’s total derivative between its initial and final values. Because partial contributions…
The document clarifies where to obtain the Fama–French value factor, HML, and how it relates to portfolios sorted by company size and book-to-market. The six size and book-to-market portfolio returns can be used to reproduce HML, so labels such as the…
The document reports an empirical research question about Indian firms, examining financial constraints, research and development spending, and stock returns. The researcher says the constraint index was built using approaches associated with Kaplan and…
The document raises a question about how to interpret a passage on stock return comovement and factor models. The cited example imagines a characteristic that predicts higher average returns, such as ticker-letter position, but does not necessarily cause…