Options risk
A 0.62 delta means nothing on its own. In dollars it might be 37% of your account riding on one stock.
The Greeks are usually taught per contract and per unit, which is mathematically tidy and practically useless. A delta of 0.62 does not tell you what happens to your account if the stock moves 1%. Converted to dollars, the same numbers answer the only question that matters: what is at risk, and to what.
Per-share delta times 100 times contracts gives share-equivalent exposure. Multiply by the price to get it in dollars:
dollar delta = delta × 100 × contracts × spotThat position behaves like $74,400 of stock. If your equity is $200,000, a single option position is carrying 37% of your account in directional exposure — a fact entirely invisible if you were looking at "3 contracts".
Summed across every position, net dollar delta is your actual market bet. Long stock, short calls and a hedge collapse to one number, and it is frequently much larger than people expect.
Delta is not constant. Gamma measures how much it moves as the underlying moves — usefully expressed as the change in dollar delta per 1% move.
Long gamma means your exposure grows in your favour: you get longer as it rises. Short gamma — which is what selling options gives you — means the opposite. A short call position that looked comfortably hedged becomes progressively shorter as the stock climbs, and the hedge you set at the start is wrong precisely when it matters.
Short gamma is the structural risk in every premium-selling strategy, the wheel included. It is not a reason to avoid it, but it is the reason positions that were fine on Friday can be uncomfortable on Monday.
Theta in dollars is straightforward — how much the position gains or loses per day from decay alone, holding everything else constant:
dollar theta = theta × 100 × contractsThe trap is reading theta as income. It is only realised if nothing else moves, and it is the compensation you are paid for being short gamma. A book showing +$300/day of theta is also a book that loses substantially on a sharp move. The two are the same trade viewed from different angles.
Vega is P&L per one-point change in implied volatility. Short options are short vega: you profit as IV falls and lose as it rises.
This is what makes selling into a spike feel so good and end so badly. You collect elevated premium, then the event lands, IV keeps climbing, and the position loses on vega faster than theta can repair it. Knowing your dollar vega tells you how much a 5-point IV move costs before you find out empirically.
Individually they are trivia. Together they describe the position you actually have.
Greeks are model outputs, not measurements. They depend on an implied volatility input, and IV for illiquid strikes is often interpolated or stale. Treat them as well-informed estimates that are directionally reliable and precisely wrong — useful for sizing and for spotting concentration, not for pretending to four decimal places.
Your position's directional exposure expressed as an equivalent stock amount: delta × 100 × contracts × spot. It answers what actually moves if the underlying moves.
Because your exposure worsens as the market moves against you. Short calls get shorter as the stock rises, so a hedge set at the start becomes inadequate exactly when it is needed.
Only if nothing else moves. It is the compensation for being short gamma and short vega — the same trade seen from a different angle, not a separate revenue stream.
How much a one-point change in implied volatility costs or earns. Short-premium books are short vega, which is why selling into a volatility spike can lose even when the direction is right.
They are model estimates driven by an IV input that may be interpolated or stale for illiquid strikes. Reliable for sizing and concentration; not precise to the decimal.
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Open the live demo — no signupEducational only. Nothing here is investment, financial, legal or tax advice, and none of it is a recommendation to trade. Figures are worked examples, not forecasts. Verify against your broker before acting.