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.
20,364 documents
The discussion examines why replacing a vanilla option at one strike with a strip of options across nearby strikes can reduce the sharp gamma concentration near expiry. It offers two related explanations: a strip distributes exposure across strikes, and as…
The question asks how long it takes a stock’s historical price to reach a chosen level. The answer explains that there is no model-free estimate: the waiting-time distribution depends on assumptions about how prices evolve. Under an arithmetic Brownian…
The document asks why fitting an autoregressive model of order one to stock prices can yield a high test-set R-squared while fitting the same form to returns can yield a negative score. An AR(1) regression predicts the current observation from its lag, but…
The document uses a one-period, two-outcome stock model to show how stock and call positions can produce a payoff that is the same in either market outcome. With the stock ending above or below the strike, the call’s payoff differs across states. Choosing a…
The document considers how to define carry for a USD payer swaption with a six-month expiry and a ten-year underlying swap. It questions a simple calculation based on subtracting a short-term LIBOR fixing from a ten-year yield, and whether that spread alone…
The document explains how trading in over-the-counter fixed income markets differs from trading listed equities. Rather than relying on one central exchange order book, dealers may maintain their own bond inventories and pricing books, especially for…
The note explains the CBOE Put Protection Index as a tail-protection strategy: it holds exposure to the S&P 500 and buys a monthly put struck out of the money. The put premium reduces returns in ordinary markets, while the option can cushion losses when the…
The note addresses whether Excel’s YIELD function can calculate the yield of an Italian government bond that pays coupons semiannually while its yield convention uses annual compounding. It explains that the bond’s price equation must discount each coupon…
The note gives an econometric rationale for adding lagged versions of predictors to a recession classification model. Its example is the yield curve: an inversion may precede a downturn by many months, so the curve observed earlier can be relevant to whether…
The note explains the inverse relationship between a bond’s yield to maturity and its price, then defines Macaulay duration as the cash-flow-weighted average time until payments are received. Under continuous compounding, bond price is the sum of discounted…
The document challenges the idea that fitting a convex curve in strike-implied-volatility space guarantees an arbitrage-free option surface. Implied volatility need not itself be convex for market prices to be free of arbitrage, and convexity of implied…
The document presents two ways to price a forward-start call whose payoff depends on the asset price at the start date as well as at expiry. One approach conditions on the information at the forward start date and rewrites the value using the price of an…
The document shows how Brownian motion's quadratic variation leads to the identity for the Itô integral of Brownian motion against itself. Applying the finite-increment expansion of one half of the squared Brownian level separates the expression into a sum…
The note explains why drift is often neglected when modeling asset prices at very short time intervals. For geometric Brownian motion with constant drift and volatility, it compares how each component scales as the interval shrinks: drift scales linearly…
The document considers whether Monte Carlo simulation can be applied directly to discrete stock percentage changes rather than to stock prices. The response highlights a key distinction between simple returns and the log returns used in geometric Brownian…
The document distinguishes estimating volatility with a GARCH model from forecasting future volatility. It also considers realized volatility calculated from high-frequency price observations as another way to quantify volatility. Its central point is that…
The document asks how to predict whether bank customers will remain active, using their account movements, and points toward customer activity or churn analysis as the problem area. It recommends multinomial logit and probit models as statistical methods to…
At expiration, a call with a zero strike pays the stock price when the stock price is nonnegative. The discussion asks whether this means the option should be worth the stock itself before expiration, and whether shareholder rights or counterparty risk…
The question describes an energy option that runs across several months. For each month, its strike resets to that month’s first-of-month index, and daily settlements below that level generate a payoff based on the difference. The question asks how to value…
The discussion responds to a request for learning materials on stock-price forecasting with artificial neural networks, LSTMs, regression, and other predictive methods. It recommends two practical books: one covering modern forecasting models, including…
A backtest that selects stocks using today’s market capitalization can exclude companies that later failed or fell out of the universe, while favoring firms that grew into it. This survivorship bias can make historical performance look too strong. The…
The document defines an affine term structure model through the relationship between bond yields and model state variables. In the simplest formulation, a zero-coupon bond price is exponential in a maturity-dependent constant and the short rate; taking its…
The document addresses why the Black–Scholes call formula contains different volatility adjustments in d1 and d2 under risk-neutral pricing. It outlines a derivation route: solve the stock price process with its drift set to the risk-free rate, then express…
The document explains how factor models can help identify risks and return patterns in an equity portfolio. It contrasts return-based analysis, which regresses portfolio returns on candidate factors, with holdings-based analysis, which aggregates exposures…