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 why a high correlation between a call option’s price and its underlying stock does not conflict with a much smaller option delta. Correlation describes how consistently the two prices move together, while delta estimates the option’s…
The document examines how to estimate a stock correlation matrix when securities have different history lengths and those histories may cover different market regimes. It outlines several approaches: truncate all series to a common period, use…
The document answers whether an R package is needed to estimate a conditional autoregressive range model. It describes the CARR approach as applying a GARCH-style specification to price ranges rather than to returns. The range is formed from the maximum and…
The document explains how to calculate covariance between two portfolios from their asset weights and a covariance matrix. The key is the order and orientation of the vectors: use the first portfolio's weights as a row vector, multiply by the asset…
The document considers a discrete random walk with independent, identically distributed increments that have positive mean under the original probability measure. It explains that a candidate measure can make the process a martingale by giving each next…
The document outlines how to approximate critical values for an augmented Dickey–Fuller test by simulating the test statistic under its null hypothesis. The test is based on a regression for the change in a series that includes its level, an intercept and…
The document describes why financial institutions clean vendor and market data before using it in quantitative models. It distinguishes high frequency trade and quote records from reference data such as dividends, maturities, coupons, and amortization…
The document raises questions about interpreting an optimal stopping value function, the conditioning notation, and why a strategy that waits one time step is valued by an expectation over future states. It also asks whether the inequality between the…
The document asks whether negative state prices, which may appear when extracting risk-neutral distributions from option prices, can have an economic interpretation. It describes a state price as the current value of a claim paying one unit in a particular…
The document considers whether countries or exchanges have banned algorithmic trading and whether such cases could support a comparison of markets. The responses report no known current exchange that operates only through traditional pit trading, making a…
The document frames look-ahead leakage checks as mutation testing. At a historical cutoff, a valid mutation preserves information available at that time while changing only future data; if the historical artifact changes, this suggests the pipeline used…
The document asks whether portfolios built from simple rules should be called efficient. In Markowitz portfolio theory, efficiency has a specific meaning: for a given expected return, a portfolio has the lowest possible risk, placing it on the efficient…
The document addresses how to measure more than the largest drawdown: it seeks the count, average depth, and average length of drawdown episodes that exceed a chosen duration threshold. It presents two approaches using price data in Pandas. One calculates…
The document asks how to create a QuantLib business calendar from a supplied list of holidays and weekends when standard country or currency calendars do not match the relevant market schedule. The answer shows the basic approach: start with a weekends-only…
The document examines a beginner’s attempt to use a fast Fourier transform (FFT) on Apple’s adjusted closing prices, including plots reconstructed with only a few frequency components. The resulting curves fall sharply near the end of the sample, prompting a…
The document compares discounted cash flow intuition for stocks and bonds with derivative pricing. For an option, the future payoff is uncertain and depends on an underlying asset, so a discounted-cash-flow approach would first require a probability…
The document raises a statistical inference problem for a time series of variance risk premia derived from options and realized variance, following Carr and Wu. The author wants to assess whether the series has a statistically significant mean and considers…
The document surveys ways to measure stock-market liquidity beyond the Amihud measure and bid-ask spreads. It groups candidate measures into spread proxies and price-impact proxies, naming Effective Tick, Holden, LOT variants, Roll, Gibbs, zero-return…
The document describes a replication attempt involving empirical equity premium prediction. It calculates a dividend-inclusive return from consecutive index prices, adds dividends to the ending index value, converts the resulting return to logarithms, and…
The document explains the usual debit and credit rules through two perspectives: historical left and right entries in T accounts, and the accounting equation. Assets increase with debits because they sit on the equation’s left side, while liabilities and…
The document outlines how to price American options when the underlying pays discrete dividends. Because exercise may be optimal before expiration, the problem is treated as an optimal-stopping problem. A numerical grid method, such as a recombining tree or…
The discussion corrects a misunderstanding about the Heath–Jarrow–Morton framework. The familiar expression that determines the forward-rate drift from its volatility applies under the risk-neutral measure, where it is part of the no-arbitrage restriction.…
The document explains how an exponential moving average can appear before a chart contains a full nominal lookback period. One answer describes a finite-window exponential weighting scheme: weights are normalized across the available observations, and the…
The document examines why a two-stock tangency portfolio calculation produces negative variance while deriving a capital market line. The proposed procedure computes expected returns and variances, forms a covariance matrix, applies its inverse to excess…