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.
5,922 documents
The document asks what recent ideas might significantly change portfolio theory, portfolio selection and optimization, or equity valuation. It does not present a particular strategy or analysis; instead, a respondent suggests several areas to investigate,…
The document explains how to decompose portfolio risk into the component associated with a world equity index and residual risk when only expected returns and a covariance matrix are available. For each asset, its beta to the world index can be obtained from…
The document explains why Fama–French portfolio construction uses different size breakpoints in U.S. and international equity samples. In the U.S., the size breakpoint is calculated from NYSE stocks and then applied to the broader NYSE, AMEX, and NASDAQ…
The document explains how asynchronous market closes can distort factor model estimation for global equities. In a cross-sectional model, factor returns and asset-specific residuals are estimated from asset returns and exposures; return series then inform…
The document asks how to infer an average one-year transition matrix when multiplying three annual matrices produces a three-year transition matrix. The response proposes taking a matrix cube root: if the relevant matrix can be diagonalized with distinct…
Factor loadings describe how modeled risk factors contribute to a credit outcome, though the term can refer to different quantities in different model classes. In a Cox-style default framework, factors may influence a firm-specific process that declines…
The document asks how to impose an upper weight limit for a particular asset while tracing a mean-variance efficient frontier with CVXOPT. The example sets up a quadratic program with a covariance matrix, expected returns, inequality constraints, and…
The document distinguishes several ways to aggregate stock performance over a period. Taking the percentage change of an arithmetic average of share prices produces the return of a price-weighted basket with a fixed number of shares in each constituent.…
The document addresses how a limited stock portfolio optimized for the highest Sharpe ratio relates to the CAPM market portfolio and the efficient frontier. It explains that an efficient risky portfolio can be combined with a riskless asset, such as cash, to…
The document frames a choice between total return indices, which account for dividends, and price indices, which track price changes. It asks which index is appropriate for portfolio construction and risk management, and proposes that long-term investors…
The discussion asks what the security market line adds beyond estimating expected returns directly. The answers connect the line to CAPM: in the model, it relates an asset’s expected excess return to its market beta, providing a benchmark for comparing an…
The document asks why the Ledoit-Wolf covariance shrinkage method, using a single-index factor model target, produces an optimal shrinkage intensity of order K/T. The author understands much of the derivation but is uncertain how the asymptotic result…
The document discusses how near-zero yields affect strategic asset allocation, especially for pension funds that use capital market assumptions and constrained mean-variance optimization. It notes that starting bond yields have historically helped forecast…
The document considers how to estimate a basket put option’s price sensitivity to changes in the weights of its underlying assets. It describes simulating asset prices jointly from assumed returns, volatilities, and correlations, then calculating the…
The document considers whether a discounted cash flow model can use a changing weighted average cost of capital during its explicit forecast period. The proposed approach would update equity cost by relevering beta each year, adjust debt cost as capital…
The document explains how a statistical arbitrage trade using principal-component eigenportfolios can pair an individual stock position with positions in portfolios representing common movements across stocks. In the paper’s sector or industry approach, the…
The document describes a data-processing problem involving a wide monthly return table with more than a thousand company columns and an eleven-year sample. The goal is to calculate a rolling cumulative return over the previous twelve months, with a one-month…
The document describes a systematic equity portfolio that selects the highest-scoring stocks and rebalances monthly against the MSCI World benchmark. Because holdings and weights may change substantially at each rebalance, the author wants to attribute each…
The document explains why forecast combination weights are sometimes constrained to sum to one, and why that constraint is not universally optimal. A sum of one preserves the level and unbiasedness of forecasts when the target has a nonzero mean. For…
The document surveys ways to quantify whether a group of stocks moves more or less together over time. Its main measure is realized cross-sectional return dispersion: at each time point, calculate the standard deviation of returns across the stock universe.…
The answer separates mean-variance portfolio choice from asset pricing. Mean-variance optimization describes how an investor chooses a portfolio given return distributions and preferences. It does not, by itself, dictate how expected returns relate to risk.…
The document describes a stock momentum strategy that buys the strongest recent performer and shorts the weakest, while using overlapping holding periods. Each month, one cohort is replaced, so the portfolio contains positions initiated at different dates.…
The document considers how to measure a trading desk’s monthly performance when daily net banking income and credit risk capital are available. It contrasts dividing month-end income by month-end capital with calculating daily income-to-capital ratios and…
The discussion considers whether portfolio managers’ behavioral biases can be scored objectively and compared across managers. Suggested observable patterns include stronger returns near quarter or year ends, large funds’ allocation shifts preceding similar…