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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