Questions tagged [models]

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55 votes
7 answers
6k views

Paradoxes in quantitative finance

Everyone seems to agree that the option prices predicted by the Black-Merton-Scholes model are inconsistent with what is observed in reality. Still, many people rely on the model by using "the wrong ...
37 votes
5 answers
7k views

Why aren't econometric models used more in Quant Finance?

There is a big body of literature on econometric models like ARIMA, ARIMAX or VAR. Yet to the best of my knowledge practically nobody is making use of that in Quantitative Finance. Yes, there is a ...
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33 votes
3 answers
8k views

How do we use option price models (like Black-Scholes Model) to make money in practice?

In quantitative finance, we know we have a lot of option price models such as geometric Brownian motion model (Black-Scholes models), stochastic volatility model (Heston), jump diffusion models and so ...
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27 votes
5 answers
14k views

Is there a standard model for market impact?

Is there a standard model for market impact? I am interested in the case of high-volume equities sold in the US, during market hours, but would be interested in any pointers.
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27 votes
6 answers
4k views

Model Validation Criteria

Let's say I have a brand new fancy model on some asset class (calibration porcedure included over a set of vanilla options) in which I truly believe I made a step forward comparing to existing ...
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24 votes
2 answers
2k views

Why isn't the Nelson-Siegel model arbitrage-free?

Assume $X_t$ is a multivariate Ornstein-Uhlenbeck process, i.e. $$dX_t=\sigma dB_t-AX_tdt$$ and the spot interest rate evolves by the following equation: $$r_t=a+b\cdot X_t.$$ After solving for $X_t$ ...
23 votes
2 answers
4k views

Which interest rate model for which product

Given the multitude of existing interest rate models (ranging from simple to very complex) it would be interesting to know when the additional complexity actually makes sense. The models I have in ...
  • 3,347
20 votes
6 answers
3k views

George Soros models

Mr. Soros in his books talked about principles which are not used by today's financial mathematics — namely reflexivity of all actions on the market. Simply it can be given by following: ...
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17 votes
3 answers
1k views

Operating parameters of market makers?

I'd like to get a feel for the operating parameters of official market makers. I'm looking more for discerning characteristics, rather than exact numbers or an exhaustive list of each MM. Examples: ...
17 votes
3 answers
806 views

Discrete-time model: stock dynamics

I am working in the area of probability theory and for a case study I would like to make some calculations in finance. Since I am developing theory for the discrete time, I am interested in models for ...
  • 2,631
14 votes
4 answers
3k views

Implementing a Fast Fourier Transform for Option Pricing

So, I'm in need of some tips regarding a small project I'm doing. My goal is an implementation of a Fast Fourier Transform algorithm (FFT) which can be applied to the pricing of options. First ...
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13 votes
1 answer
703 views

What methods do I need to learn in order forecast asset price movements?

What are the standard models used to forecast asset price movements? For example, if I were to trade an option, what model would I use in conjunction with option pricing models to forecast the stock ...
13 votes
3 answers
1k views

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 ...
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12 votes
1 answer
312 views

How should FX options be priced when a currency is artificially capped?

The question is inspired by yesterday's (06/09/11) historic announcement by the Swiss National Bank that it would impose a ceiling on the franc of 1.20 against the euro. I would like to know if there ...
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10 votes
2 answers
901 views

Risk Model Validation

I have such a general question regarding risk model validation. Which tools are most often used for validation and how does the process work? Could you recommend any books that focus on this topic?
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9 votes
3 answers
2k views

Does the gamma function have any application in quantitative finance?

I was looking into the factorial function in an R package called gregmisc and came across the implementation of the gamma function, instead of a recursive or iterative process as I was expecting. The ...
9 votes
1 answer
1k views

Monte carlo portfolio risk simulation

My objective is to show the distribution of a portfolio's expected utilities via random sampling. The utility function has two random components. The first component is an expected return vector ...
9 votes
2 answers
1k views

Interest Rate Models cheat sheet - Need for advice

I'm trying to get through the litterature of interest rate models for some time now. As I don't have any experience working with them, I started looking for some kind of a cheat sheet that would ...
9 votes
1 answer
804 views

Are there any standard MBS coupon stack models?

I need to model MBS coupon stack prices. It would not be difficult to create something from scratch, but I don't want to re-invent the wheel (and explain why I did) if a somewhat standard model ...
8 votes
2 answers
643 views

Confusion with volatility smiles implied by different models

I am reading a book "The concepts and practice of mathematical finance" by Mark Joshi. In Chapter 18 he discusses the shapes and dynamics of smiles under different models. I do not understand what is ...
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8 votes
1 answer
556 views

What are the empirical limitations to testing market efficiency?

I have encountered a rather elegant argument about the limitations of empirically testing for market efficiency, involving the central point that we do not know whether a result is due to the "true ...
8 votes
1 answer
674 views

Bermudan Swaptions - Payer vs. Receiver (LGM)

There is abundant literature discussing the pricing of Bermudan swaptions and the relevance of single-factor Markov-functional models (e.g. LGM) versus multi-factor market models (e.g. LMM). From a ...
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8 votes
1 answer
2k views

Multi Fractals Models

From a quant point of view, how would you explain Multi Fractals Models in few words ? I have the level to take these courses, but won't be able to do it next year, so I want to know what I am missing....
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8 votes
1 answer
343 views

What are some quantitative ways to obtain the view confidences in Idzorek's version of Black-Litterman?

I'm using Idzorek's version of the Black-Litterman model for estimating asset returns. Idzorek's version bypasses the need to estimate directly the covariance matrix $\Omega$ of errors in the various ...
8 votes
2 answers
2k views

KMV-Merton Probabilties of Default vs Moody's EDF

Moody's used to publish probability of default estimates from their Moody's EDF model, but they have temporarily discontinued it. I understand that the Moody's EDF model is closely based on the Merton ...
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7 votes
2 answers
243 views

Question about equations and risk factors.

Say I have two risk factors $X_1$ and $X_2$. Standard deviation for $X_1$ is $\sigma_1$ and $\sigma_2$ for $X_2$. Furthermore, $X_1$ has a mean of $\mu_1$ and $X_2$ has a mean of $\mu_2$. Correlation ...
  • 717
7 votes
4 answers
6k views

Typical coefficients uses in square-root model for market impact

The square-root model is widely used to model equity market impact. It assumes that volatility, traded volume, total volume, and a spread cost are the drivers of slippage. Jim Gatheral has an ...
7 votes
0 answers
235 views

Seeking criticism of model assumptions

I have been trying to publish a new calculus and options model for seven years. I have been consistently desk rejected, so what I am trying to do is get criticism of my assumptions because they ...
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6 votes
2 answers
1k views

What are the significant implications of the long-run average variance rate and why Engle won the Nobel Prize for ARCH model development?

In a ARCH(m) model we have $$ \sigma_n^2=\sum_{i=1}^{m} \alpha_i u_{n-i}^2 $$ where $u_i$ is defined as the continuously compounded return during day $i$ (between the end of day $i-1$ and the end of ...
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6 votes
1 answer
1k views

Is Behavioral Finance relevant to quants?

This topic has been prompted by the following question: Measuring Behavioral Finance Effects in Fund/Portfolio Manager Analysis After reading it and the comments below I started thinking whether ...
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6 votes
1 answer
1k views

How to find optimal look back in quant trading models

I'm in the process of building a quantitative trading model, I want to improve on the way in which I decide upon a look back length for the indicators. I understand the different pros/cons for very ...
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6 votes
2 answers
561 views

Architecture of a global pricing library with immutable payoffs

By global pricing library I mean a library handling equity, rate etc, hybrid products having several models (BS, LV, SV, LSV) having several numerical methods (analytic formula, MC, PDE FD/FE) I ...
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6 votes
2 answers
882 views

What is model-free finance?

I have run across the term "model-free finance" (e.g. there was a Thalesian talk in London recently), yet haven't found any real definition of it nor anything really substantial. Could you point me ...
  • 27.1k
6 votes
1 answer
228 views

How to scale option pricing components in regard to time

I am looking at closed-form options approximations, in particular the Bjerksund-Stensland model. I have run into a very basic question. How should I scale the input variables in regard to time? My ...
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6 votes
0 answers
383 views

How are quants able to verify whether their calculated prices are any good

This question is related to the discussion on Model Validation Criteria However it appeard to be very high level to me and I would like to go more into detail. Not working at a pricing desk the ...
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5 votes
2 answers
340 views

How to derive this approximation of the risk-neutral expectation of the variance?

On the paper Bollerslev, Tauchen and Zhou (2009 RFS) the authors say about equation (15): The corresponding model implied risk-neutral conditional expectation $$E^Q_t(\sigma^2_{r,t+1})=E_t(\sigma^...
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5 votes
2 answers
1k views

Ideas about Stochastic volatility models

I am currently working on comparing different models for modelling the volatility and then pricing vanilla options (I use option prices on real stocks in order to calibrate my models and then I ...
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5 votes
2 answers
669 views

Intuition behind interest rate models

I am modelling the 3M yield of US Treasuries using an ARMA/ GARCH approach. Most interest rate models (e.g. Vasicek) describe the process as follows: $r_{t}-r_{t-1} = some ARMA+ \epsilon_t $ ...
5 votes
1 answer
431 views

Relation between price changes and trading volume (market impact)

It is quite a well-know phenomenon that trading volume has an impact on a stock price: the more you buy the higher is a price because of demand increment. I'm wondering about models that can describe ...
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5 votes
1 answer
267 views

Can binary model lead to non-normal distribution?

If we suppose an instrument goes up or down 1 tick per $\Delta t$ (binary model), its long term distribution will be normal, per the Central Limit Theorem. However, suppose we model as follows: The ...
user avatar
5 votes
1 answer
177 views

Are processes with independent increments (which are not Lévy) used in finance?

From Jacod and Shiryaev's Limit Theorems for Stochastic Processes, we get the following definitions. Definitions: A process with independent increments (abbreviated PII) $X = (X_t)_{t \geq 0}$ on a ...
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5 votes
0 answers
365 views

A question about the Grossman-Miller Market Making Model

I don't have any solid background in finance, but I have a strong mathematics and physics background. I am reading Algorithmic and high-frequency trading from A.Cartea, S.Jaimungal and J.Penalva, CUP (...
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5 votes
0 answers
112 views

What are the requirements for no arbitrage to exist in a chaotic/dynamical system?

Consider the continuous dynamical system $$\alpha\ddot{S}+\dot{S}=\mathcal{F}(S,t),$$ such that $\alpha\in\mathbb{R}$ and $\mathcal{F}$ is real and analytic. We assume that if a solution for $S$ ...
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4 votes
2 answers
248 views

what does the cover page of Guyon and Labordere's Nonlinear Option Pricing represent?

It could be a bit offtopic, but I don't see the link between the contents of the book and the cover page. Thanks
4 votes
1 answer
557 views

What does it mean that model can reflect the ”volatility smile”

I know that implied volatility is the value for which the Black Scholes model returns the correct option price. I also know that if we plot the volatility on the strike price chart, we will see "...
  • 423
4 votes
1 answer
983 views

mortgage prepayment model

I am trying to develop my own MBS prepayment model. I am confused by the terms SMM and CPR. Are they estimates/models in themselves or are they ACTUAL data for the MBS pool. where can I find actual ...
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4 votes
4 answers
257 views

Does the non-causal nature of quant models limit their applicability?

I understand that to describe financial data, we build stochastic models and calibrate their parameters to past data. When coming up with new algorithms, we rely on rigorous backtesting to convince ...
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4 votes
1 answer
218 views

What are some common models for one-sided returns?

One typically models the log returns of a portfolio of equities by some unimodal, symmetric (or nearly symmetric) distribution with parameters like the mean and standard deviation estimated by ...
  • 2,806
4 votes
1 answer
68 views

Negatively Correlated Assets with similar medium-term trends

Theoretically, one could have stock prices with returns $\rho_1(k)$ and $\rho_2(k)$ having mean values $\mu_1$ and $\mu_2$, but still be negatively correlated with $$ \mathbb{E}[(\rho_1(k)-\mu_1)(\...
4 votes
1 answer
1k views

Derivation of the Nelson-Siegel model and proof of arbitrage

1. I am looking for a derivation of the Nelson-Siegel model $y(m)=a+b\left( \frac{1-e^{-\lambda m}}{\lambda m}\right)+c\left( \frac{1-e^{-\lambda m}}{\lambda m} -e^{-\lambda m} \right)$ It is ...