Margin and Margin Calls: How Borrowing to Buy Stocks Works
How buying on margin works: Reg T’s 50% rule, FINRA’s 25% maintenance minimum, what triggers a margin call, and why brokers can liquidate without notice.
investing basics
S&P 500 Inclusion: What Really Happens When a Stock Joins
How a stock actually gets added to the S&P 500, what the historical “index effect” was, and why recent research finds that pop has largely vanished.
The VIX Explained: How Wall Street’s Fear Gauge Works
What the VIX really measures, how it’s built from SPX options, why VIX ETPs like VXX lose money over time, and the common mistakes traders make.
Sharpe Ratio Explained: Measuring Risk-Adjusted Returns
How the Sharpe ratio works: the formula, a worked example, common pitfalls, and why William Sharpe himself warned against trusting a single number.
Secondary Stock Offerings: Dilution, ATMs, and Greenshoes
How public companies issue new shares after their IPO, why the stock usually falls on the announcement, and what ATM offerings and greenshoes really do.
TIPS Explained: How Inflation-Protected Treasuries Work
How Treasury Inflation-Protected Securities work — principal adjustment, real yield, breakeven inflation, taxes, and where TIPS fit in a portfolio.
Implied Volatility Explained: How Options Price Future Moves
What is implied volatility? How does it differ from realized volatility, drive the VIX, and shape every options trade? A best-in-class explainer with worked numbers, IV rank, skew, and term structure.
Options Greeks Explained: Delta, Gamma, Theta, Vega
What delta, gamma, theta, vega, and rho actually mean — with worked examples from the Options Industry Council and a 30-day call snapshot.
Repo and Reverse Repo Explained: How Funding Plumbing Works
How the repo market actually works — collateral, haircuts, SOFR, the Fed’s ON RRP, and why the $2.5T overnight RRP facility drained to almost zero in 2026.
Bond Duration Explained: Why Yields Move Bond Prices
Bond duration measures how much a bond’s price moves when yields change. Here’s the math, a worked example, and why long Treasuries got crushed in 2026.