No that's not how ITM chances are calculated. Bell curve
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Key number is the one standard deviation move. I don't do a lot of research into this but the basics I get. Since the dealers already calculated it and used it to price options, a shortcut that traders frequently use is (ATM call premium + ATM put premium) * 0.85 = 1 standard deviation
For example, as I'm typing this, 1/27 128C + 128P = $14. $14 * 0.85 = $11.9. It means the stock has 68% chance of remaining in the 116.1 - 139.9 range (-/+ 1 standard deviation), 95.4% chance of remaining in the 104.2 - 151.8 range (-/+ 2 standard deviations). Which means only 2.2% chance of going over 151.8. There is a formula to calculate the chance of over/under any certain strike but
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