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.
21,023 documents
The document explains a standard regression approach for estimating a portfolio’s CAPM alpha. It recommends calculating monthly excess returns for the portfolio and market, then regressing portfolio excess returns on market excess returns. The regression…
The accepted answer explains how to minimize conditional value-at-risk, also called expected tail loss, using a scenario-based linear program. It introduces portfolio weights, a variable representing the value-at-risk threshold, and one auxiliary variable…
The document describes a simulation designed to compare covariance transformations for minimum-variance portfolio construction. For each lookback window, the author samples portfolios of 100 assets, estimates a sample covariance matrix, transforms it, and…
The document proposes a quadratic program for finding an efficient frontier between expected alpha and a portfolio’s residual variance relative to a benchmark. It expresses residual variance as portfolio covariance risk less the benchmark variance scaled by…
The document frames an out-of-sample estimation question for a cointegration pairs strategy. In sample, the proposed workflow applies the Engle–Granger two-step procedure, estimates a hedge coefficient for the spread, and standardizes that spread using its…
The discussion collects several ways to transform stock prices for analysis. Suggested measures include log prices, price deviations from a mean, standardized deviations using a standard deviation, log-price deviations from a mean, log returns, percentage…
The discussion explains reflexivity as a feedback loop: traders form expectations from information and prices, act on those expectations, and thereby change prices and later beliefs. It points to Keynesian beauty contests, game theory, agent-based models,…
The document compares two CAPM regression forms: one uses the asset's return in excess of the risk-free rate, while the other regresses the raw asset return on the market's excess return. It explains that, when the same observations and regressors are used,…
The document asks how to construct an efficient frontier by optimizing portfolio weights at specified volatility levels, rather than relying on random sampling. It describes maximizing expected portfolio return subject to a volatility ceiling and nonnegative…
The document explains why equal percentage losses and gains do not cancel when returns compound. After a loss, the same percentage gain applies to a smaller capital base, so the account remains below its starting value. It gives a formula for the number of…
The document asks how to interpret the Spearman correlation used in the Fundamental Review of the Trading Book to compare hypothetical P&L (HPL) with risk-theoretical P&L (RTPL). The stated procedure ranks each series in ascending order, then applies the…
The problem describes a seller who observes a sequence of prices for different future delivery days and must choose when to commit to selling. Prices for each fixed delivery date are assumed to follow a martingale. The proposed approach begins with a Bellman…
The document asks whether trading strategies can remove volatility clustering—the persistence of large or small absolute returns—and what that would imply for diversification and alpha. It contrasts the CAPM view of market exposure with anecdotal claims that…
The discussion considers a daily strategy that holds positions for one day while using an indicator built from a five-year price history. Because adjacent indicator readings share much of the same input data, they are strongly serially dependent. The…
The note asks whether traditional factor models become less adequate as markets grow more complex and new return patterns emerge. It cites the Fama-French three-factor model, which captures broad cross-sectional return patterns in the mid-1990s but does not…
The document asks how to estimate the variance of monthly returns when a return series includes both monthly observations and one quarterly aggregate. The proposed response describes a moment-based approach under temporal independence: infer the quarterly…
The document asks why credit rating grades can span different widths of probability of default (PD). Its example mapping assigns relatively narrow PD intervals to stronger grades and wider intervals to weaker grades, and raises the possibility that a PD…
The document poses a fixed-income modeling question: whether a bond spread curve can be converted into a credit curve by applying the same bootstrapping function used for a CDS par-spread curve. The setup assumes a standard CDS framework with piecewise…
The document considers how to estimate a portfolio variance-covariance matrix when assets began trading at different times. One direct method is to use only the period in which every asset has data, which avoids mismatched histories but discards older…
The document asks how to infer a stock’s beta from return expectations and how to attribute its variance to market risk. One response writes returns as a market-linked component plus an idiosyncratic residual. Under the single-index assumptions that the…
The document examines why a derivative’s price should not depend on which other derivative is chosen to hedge volatility risk in a stochastic-volatility model. The proposed replication argument uses the underlying and a second derivative to span two Brownian…
The document describes how to express an unhedged US investment’s performance in euros. First, turn the dollar return series into a total-return price index, using an arbitrary starting value such as 100. Next, convert each index value into euros using the…
The document explains what the ACT/360 day-count convention means when calculating interest. A year is treated as 360 units for the calculation, while elapsed time is counted in actual calendar days. As a result, a 365-day period accrues interest for 365/360…
The document considers how to recover the risk-neutral density of an underlying at a given expiry from call option implied volatilities across strikes. It describes converting each implied volatility into a Black–Scholes call price, then applying the…