# Questions tagged [put]

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### American put option. Exercise time is a random variable, calculation of expected payoff

I got an American put option, where the payoff is $V_\tau = \max(K - X_{\tau}, 0)$ and $X_{\tau}$ is the price of an underlying at the stopping time $\tau < T$. The underlying follows a standard ...
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### Feynman-Kac to derive stochastic representation

$u_t + \frac{1}{2}\sigma^2x^2u_{xx} - \alpha + \lambda((K_d - x)^+ - u) = 0$ with terminal condition $u(T, X) = (K_m - X(T))^+$ $dX = \sigma X(t)dW_t$ $\alpha$ and $\lambda$ are constants Ok so ...
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### How can the solution to a optimal stopping problem be superharmonic?

A general result (Peskir and Shiryaev: Optimal Stopping and Free Boundary Problems, 2006, Thm. 2.4, Page 37) is that the solution to an optimal stopping problem $\sup_\tau EG(X_\tau)$ where $X$ is ...
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### What are the main problems for calculating the implied volatility of in the money American put options?

As stated in the question I have a problem with calculating the implied volatility for in the money put options I have a data set of 2.6 million American style plain-vanilla call and put options. For ...
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### Kingdom of Denmark Nikkei put warrants

I have read in a book from Emanuel Derman that Goldman Sachs manufactured a derivative in the early 90's that consisted of buying cheap puts on th Nikkei index (and paid in Yen), combined them which a ...
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### Enron - RhythmsNet hedge

I am reading "Power Failure: The Inside Story of The Collapse of Enron" By Mimi Swartz, Sherron Watkins. In the book, the following transaction is described: Enron had USD200mn worth of futures on ...
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### Sell weekly covered calls repeatly

If underlying stock prices are random walk in short term, then it doesn't matter where the price go. What we can definitely certain, is the high Theta in ATM options. Can we repeatedly sell weekly put,...
182 views

### Perpetual American put option with zero interest rate

I want to find an optimal time when we should exercise perpetual American put option. In other words I want to maximize the following equation:  V(S) = \sup_{\tau \in \mathcal{\tau}}\mathbb{E}[e^{-...
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### Price of european call option for different strike prices

Consider two european put options with strike prices $K, J$ with $K<J$ and maturity $T$. Then the no arbitrage assumption implies $P_{K}(0)<P_J(0)$, where $P_K(0)$ denotes the price of the put ...
47 views

### What can we say about digital puts and calls with different strike prices?

I am a noob to the field of quantitative finance. I am reading this book by Mark S. Joshi. Can you help me make sense of one of the exercise questions? Here is the question (from page 40 of the book): ...
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### Reproducing a short put position using known binomial option tree

Suppose a put option follows prices according the the binomial tree I've made and posted below and consider writing a put ($S$ is the stock value, $P$ is the put value, obviously). I want to find the ...
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### VaR of protfolio with put and call

I've stumbbled into this question in a job interview and didn't know how to answer it: Calculate the VaR of a portfolio where you are long put and long a call
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### Synthetically sell to close puts in limited-margin IRA

Suppose: I bought an American put on a stock in a retail brokerage IRA, where I can't sell short or write uncovered options. The put is ITM and has served its purpose for hedging. The put is thinly ...
Why is it stated sometimes that $C - P = F$ and in wikipedia it statest that $C - P = D(F-K)$, where D is the discount factor and K is the strike (of both the call and put?). Is this just affected ...