We’re continuing the series on learning options with AI. In the previous video we covered what delta, gamma, theta and vega are using the car analogy. Today we get to my favorite part of this series: taking that theory and applying it to a real option chain on ProRealTime, using the SPY ETF and live data.
Delta: how it changes by strike
We open SPY’s option chain with 51 days to expiration. The price is at $734, so that’s our at-the-money strike.
Delta across different strikes (51 days)
Strike 734 (at the money) — delta ≈ 0.50
Strike 760 (out of the money) — delta ≈ 0.28 → roughly 28% probability SPY is above 760 in 51 days
Strike 700 (in the money) — delta ≈ 0.76 → roughly 76% probability it ends up above 700
As you can see, it’s the same logic we already covered: at at-the-money strikes, delta hovers around 0.50. The further out of the money, the lower it goes; the further in the money, the higher it climbs, because it already has a lot of intrinsic value.
A 50-day expiration isn’t the same as a 5-day one or a one-year one — you won’t find the same delta at the same strike. That’s why you should always check which expiration you’re looking at before drawing any conclusions about probability.
Gamma: acceleration, live
At that same 734 strike (at the money) with 51 days to expiration, gamma shows a certain value. If we switch the expiration to today, at that same strike gamma spikes noticeably higher — it’s the acceleration of delta, and as you get closer to expiration with the option at the money, that acceleration becomes much sharper than when there are still 51 days ahead.
It’s the speed at which the option’s price can change. The closer to expiration and the more at the money, the more it accelerates.
Theta: what you gain or lose in a day
With one day to expiration and an at-the-money strike, theta shows a meaningfully negative daily value. That means if SPY stays roughly in the same spot, you’ll have lost that amount by tomorrow if you’re a buyer — or gained that same amount if you’re a seller, simply from one day passing.
If we switch the expiration to 30 days, at that same at-the-money strike, theta drops to a much smaller value. Why is it so different? Because with only one day left, everything you had to gain or lose gets concentrated into that single day. With 30 days ahead, that daily loss (or gain) gets spread out gradually until expiration.
Vega: visualize it with the risk analyzer
Vega measures how much the option’s price changes for every percentage point implied volatility moves. To see it as more than just a number, ProRealTime’s risk analyzer lets you set implied volatility to manual mode (instead of automatic) and check exactly how the option’s price changes based on the volatility you yourself expect for that moment.
The Greeks are a dashboard you should always keep an eye on when trading options — whether you’re about to buy or sell, or you already have the position on. Even once the trade is open, keep watching how these Greeks move for you or against you — that’s why it’s worth having them properly set up on the platform from the start.
Conclusion
Seeing the Greeks with real SPY data on ProRealTime makes the theory click much better: delta changes based on how far the strike is and on the expiration; gamma accelerates near expiration on at-the-money strikes; theta favors the seller and penalizes the buyer, more sharply the less time remains; and vega connects directly to implied volatility. If you want to review the theory from scratch, check out the previous video with the car analogy. Don’t forget to comment and like to keep following the series.
