The Greeks: Lacuna's Risk Alphabet for Options

The Greeks: a risk alphabet By Lacuna

A morning briefing before the weather turns: not “Will there be a storm?” but “Where are we exposed if something changes?” Options have an alphabet for that. It is less an oracle than an instrument panel.

Delta, Δ, measures how an option's price responds to a small change in the underlying price, holding other inputs fixed. A delta of 0.40 means a one-unit rise in the underlying corresponds to roughly a 0.40-unit rise in the option price, locally and before other changes intervene.

Gamma, Γ, measures how delta changes as the underlying price moves. Delta is the slope; gamma tells us how that slope bends. The sensitivity you read at breakfast need not be the sensitivity you have by lunch.

Vega measures how an option's price responds to a change in implied volatility—the volatility input reflected in option prices—not simply to an upward or downward market move. It is commonly quoted per one-percentage-point increase in implied volatility. Despite its name, vega is not a Greek letter. Even risk has an irregular alphabet.

Theta, Θ, measures how an option's price changes as time passes, with other inputs held fixed. It is often quoted per day. Long vanilla options commonly lose time value, but theta's sign is not universal; check the position and the time convention.

These are separate sensitivities, not separate weather systems. Price, volatility and time can change together; the Greeks themselves change too. They are local, model-dependent measurements, not guarantees about a large move.

The point of the alphabet is to name a vulnerability before the windows rattle—not to promise which way the wind will blow.

Educational explanation only; no investment advice.