Optimal Shorting for IBM Put

This question focuses on when it makes sense to be a net seller of downside protection on a single-name equity option, here framed as an IBM put. The candidate has to reason about market environments where writing such a contract is attractive, in terms of the underlying stock's expected path, volatility regime, and prevailing risk sentiment. It implicitly contrasts directional bearish views with expectations about realized versus implied volatility, and about the likelihood and severity of price moves in the underlying. This style of question is common in buy-side and sell-side derivatives roles where traders must decide whether option premia are rich or cheap relative to the risks they are taking on.

Answering well relies on a clear command of the key Greeks and how they affect a short put position across different scenarios. The interviewer is looking for structured thinking around delta, vega, theta, and possibly skew and term structure, rather than slogans about "bullish on the stock." They want to see awareness of tail risk, gap risk, and margin considerations, and an ability to connect qualitative macro or stock-specific views to quantitative option exposures. A strong answer weighs trade-offs: income from time decay versus exposure to sharp downside moves.

What it tests

The value of an option is governed by its sensitivity to various market parameters, captured by the Greeks: delta (price sensitivity), vega (volatility sensitivity), theta (time decay), and rho (interest rate sensitivity). For any option position, the sign and magnitude of these sensitivities determine how the position will respond to changes in the market environment. The core principle is that by understanding the direction and impact of each Greek, you can predict when an option position will be profitable or risky. This framework is universal for all option types and positions, not just puts or shorts: the Greeks encode how each market force pushes or pulls the option's value. The reason this works is that options are nonlinear instruments whose value is a function of multiple variables, and the Greeks are the partial derivatives that describe the local slope in each direction.