Further ERM Session 1: Analysis of extreme events
This presentation is based on a part of an academic course on Further Enterprise Risk Management (Further ERM) titled ‘Analysis of extreme events’ and covers topics such as: typical univariate distributions used in practice, Extreme Value Theory (EVT) and its underlying distributions, generalised distribution fitting (e.g. to the tail of a distribution), adjusting for volatility, confidence levels, multivariate extreme value theory and implications for portfolio construction
Slides
1 | Session 1: Analysis of extreme events |
2 | The problem |
3 | Session 1: Analysis of extreme events |
4 | Univariate probability distributions |
5 | Typical (univariate) distributions used in practice |
6 | Features shared by many distributions |
7 | Underlying mathematical formulation |
8 | (Sum) stable (aka Levy-stable) distributions |
9 | Session 1: Analysis of extreme events |
10 | Extreme Value Theory (EVT) |
11 | Restatement of EVT results |
12 | Main result for block maxima |
13 | Main result for threshold exceedances |
14 | Session 1: Analysis of extreme events |
15 | How should we choose between distributions? |
16 | Various ways of fitting a (univariate) distribution |
17 | A generalised least squares approach to tail fitting |
18 | Tail weighted maximum likelihood |
19 | C.f. estimating tail using GPD distributions |
20 | Estimate the quantile that starts the tail |
21 | Combined estimate |
22 | Choosing the threshold |
23 | Judging the start of the tail |
24 | Potential weaknesses |
25 | Alternative ways of estimating VaRs etc. |
26 | Some subtleties of EVT |
27 | Session 1: Analysis of extreme events |
28 | Adjusting for volatility |
29 | Session 1: Analysis of extreme events |
30 | Confidence levels |
31 | Session 1: Analysis of extreme events |
32 | Multivariate EVT, e.g. for block maxima |
33 | EV copulas |
34 | Example EV copulas |
35 | Domains of attraction and threshold exceedances |
36 | Session 1: Analysis of extreme events |
37 | Portfolio construction |
38 | Portfolio construction - sensitivities |
39 | Incorporating fat tails: Solution A, simplest |
40 | Incorporating fat tails: Solution B, more sophisticated |
41 | Or use lower partial moments? |
42 | Estimating lower partial moments |
43 | Euler capital allocation principle |
44 | Summary |
45 | Appendix A: Modelling fat tails for individual risks |
46 | Many (most?) investment return series are ‘fat-tailed’ |
47 | Why are return series often fat-tailed? |
48 | Time-varying volatility |
49 | Explains some equity index fat fails, particularly upside |
50 | And over longer time periods |
51 | Crowded trades and leverage |
52 | Important Information |
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