# Tagged Questions

The volatility of the price of the underlying security that is implied by the market price of an option based on an option pricing model.

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### Log-normal Volatility Approximation

In a comment to this question, it is mentioned that, under the log-normal distribution, \begin{align*} vol(k) \approx vol(atm) \times \sqrt{\frac{atm}{k}}. \end{align*} Here, $k$ is the strike, $atm$ ...
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### SABR Implied Volatility and Option Prices

I am trying to understand the SABR model. Specifically, I am having difficulty to understand how to calibrate the model parameters, that is, initial variance, volatility of variance, exponent for ...
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### Variability of IVs of OTM options

I'm attempting to fit a curve through moneyness/IV datapoints of intra-day options. As you can see, the data gets sparser and more variable for highly OTM options. I'd like to argue why the outliers ...
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### How does one calibrate a stochastic volatility model?

I will try to use SABR Model to price call options in FX market. What does it mean to calibrate the model? As far as my understanding of the Wikipedia article goes, it means to estimate the parameters....
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### Lower bound of ITM Calls when computing Implied Volatility

Assuming the Black Scholes model and pricing formula of a European call option. Then, if the call is ITM, i.e. if $ln(\frac{S}{K})>0$, the $d_1$-term will go towards infinity as $\sigma$ goes to ...
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### Volatility Smile Approximation

Does anyone know what type of model is used to model the skew and IVs inside Thinkorswim platform for its volatility smile approximation? I am trying to replicate but do not know where to start. Any ...
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### why Implied Vol (VIX) increase with decrease in Stock Price or vice versa?

why Implied Vol (VIX) increase with decrease in Stock Price or vice versa? whereas Vega is positively related with change in option price to change in stock price.
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### The name conventions such as ATM, Risk reversal and Butterflies to construct volatility surface

Why people call (vol call - vol put) risk reversal when risk reversal actually is (call 25 delta -put detlta +25)? when constructing volatility surface? The vol of risk revesal should not be vol call -...
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### Hedging - calculating option prices using implied volatility surface

To hedge a strategy is it accurate "enough" to price an option using an implied vol curve vs moneyness (strike/spot) assuming sticky delta? The moneyness can be read off the chart, its corresponding ...
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### Difference between Deterministic Volatility Function approach and Ad Hoc Black Scholes?

I am thoroughly confused after reading Dumas, Fleming & Whaley (1998) "Implied Volatility Functions: Empirical Tests". Both the Ad Hoc BS Model and the Deterministic Volatility Function ...
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### Inverse Smile Volatility Ibex35

I was analysing ibex implied volatility and when I draw it I found it was reversed: X axis are the strikes and Y axis implied volatilities calculated by BS. The blue line is the spot price. Data (...
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### What kind of crisis can drag Implied Volatility down globally?

I want to trade buying long straddles with low IV ranks. I wonder what could be a crisis for me. I believe any kind of economical crisis would increase the IV. What happening could be a crisis for me? ...
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### Historical Volatility vs Implied Volatility Performance in Pricing Options

I consistently read on academic papers, when pricing options, using implied volatility is better than using historical volatility. Because, market is more "forward-looking" and historical data is "...
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### Vol surface changes as underlying moves

We market make in highly liquid, near term options markets. I want to build a risk report that tells us how our portfolio's greeks will change as the underlying moves. This is for risk management in ...