## Top new questions this week:

### Why do volatility and correlation increase in times of crisis?

can somebody please explain to me why volatility and correlation increase in times of crisis? It is connected somehow to the herding effect. But I cannot really explain it. And also why are negative ...

volatility correlation

### portfolio optimization averaging weights

I'm playing around with different portfolio optimization techniques. Amongst others I was also looking at the resampling method, especially the one described in Meucci. I have two general questions ...

modern-portfolio-theory portfolio-optimization

### How to price a path dependent exchange option using?

Assume you have two stocks $S$ and $P$ so that at initial time $t = 0$: $S_0 > P_0$. You bought an option which pays off $S_T - P_T$ as long as $S_t > P_t$ through the time $0 < t < T$. ...

options option-pricing no-arbitrage-theory

### Calibrating stochastic volatility model from price history (not option prices)

For stochastic volatility models like Heston, it seems like the standard approach is to calibrate the models from option prices. This seems a bit like a chicken and an egg problem -- wouldn't we ...

volatility stochastic-volatility

### Clarify a derivation in Pat Hagan's Convexity Conundrums

I am looking for help in understanding the algebraic derivation to go in between some of the lines in Pat Hagan's famous Convexity Conundrums paper e.g. how he goes from 3.4a to 3.5a.

mathematics

### Equivalent Definitions of Self-Financing Portfolio

Consider a multi-period model with $t=0,...,T$. Suppose there is a bond with $B_0=1$ and $B_t=(1+R)^t$ and a stock with $S_0=s_0$ and $$S_{t+1}=S_t\,\xi_{t+1},$$ with $\xi_t$ iid random ...

portfolio no-arbitrage-theory self-study

### How does Algorithmic Differentiation work and where can it be applied?

The title says it all, but let me expand on it. Algorithmic differentiation seems to be a method that allows a program / compiler to determine what the derivative is of a function. I imagine it's a ...

greeks algorithmic-derivative

## Greatest hits from previous weeks:

### What is a stationary process?

How do you explain what a stationary process is? In the first place, what is meant by process, and then what does the process have to be like so it can be called stationary?

stochastic-calculus time-series stationarity

### Switching from C++ to R - limitations/applications

I've only recently begun exploring and learning R (especially since Dirk recommended RStudio and a lot of people in here speak highly of R). I'm rather C(++) oriented, so it got me thinking - what are ...

r development

### Comparing volatility using GARCH

Hi, I am investigating if the policy of inflation targeting lowers the volatility of inflation. I have ran the GARCH regression: Inflation(t) = C + Inflation(t-1) + Inflation(t-2) + Error, but ...

volatility time-series garch econometrics inflation
 asked by Kunal Chauhan 1 vote

### Fair Price CDS Spread for a Bank

I have been using CreditGrades to calculate fair one year CDS spreads for firms. However, the authors of the model explicitly say that the model does not hold for banks or financial firms. If I need ...

derivatives cds default
 asked by varun chandra 1 vote

### Validating a Credit Scoring Model without Data

Fellow Quants, Suppose you have a credit scoring model that is developed without the aid of statistics, because (unfortunately) there is no historical default/loss data in your portfolio. The ...

models credit credit-scoring validation