Convex optimisation in financial risk management
Submitting Institution
King's College LondonUnit of Assessment
Mathematical SciencesSummary Impact Type
EconomicResearch Subject Area(s)
Mathematical Sciences: Applied Mathematics, Statistics
Commerce, Management, Tourism and Services: Banking, Finance and Investment
Summary of the impact
Prof. Pennanen and collaborators have developed mathematical models and
computational
techniques for financial risk management. The techniques allow for
quantitative analysis and
optimization of financial risk management actions in an uncertain
investment environment. The
techniques have been used by the State Pension Fund, Ministry of Social
Affairs and Health, Bank
of Finland and Pension Policy Institute. The techniques have significant
impact on practitioners and
professional services in increasing the awareness and understanding of
long-term financial risks that
are difficult to quantify with more traditional techniques. Beneficiaries
of the developed risk
management techniques include future pensioners and tax payers.
Underpinning research
The developed risk management techniques are based on the simple but
often neglected fact that
most pricing and valuation problems in the financial industry can be
treated as problems of asset-liability
management which, in turn, can be treated under convex optimisation. This
observation adds
consistency to various approaches in financial mathematics and it
simplifies many problems that are
often viewed as separate. A general overview is given in reference [4]
below. Many earlier models
concentrate solely on pricing of financial products without explicit
account of the asset management
side. Accounting standards, both in banking and insurance suffer from the
same problem. They are
often based on so called risk-neutral valuation principles or even simpler
rules of thumb that ignore
the interplay between assets and liabilities. This may lead to problems
when the pricing models fail,
as has been seen in the past.
Traditionally, the main tools in mathematical finance have come from
probability theory and
stochastics but convex analysis is turning out to be equally useful. For
example, general
characterisations of the no-arbitrage property of a perfectly liquid
market model in terms of
martingale measures are largely based on separation theorems for convex
sets. The optimisation
perspective brings in variational and computational techniques that have
been successful in more
traditional fields of applied mathematics such as partial differential
equations and operations
research. Techniques of convex optimisation allow for significant
generalisations to the classical
models of perfectly liquid financial markets. We have applied convex
analysis techniques to extend
fundamental results in mathematical finance to markets with transaction
costs and portfolio
constraints that are often encountered in practical applications. New
models with nonlinear illiquidity
effects are developed in references [1,3,5,6] below.
Techniques of convex optimisation provide new possibilities also for
financial risk management in
practice beyond the techniques of stochastic analysis alone. The presence
of stochastic elements in
a model results in difficult, often infinite-dimensional optimisation
problems that require specialised
optimisation techniques. We have developed new computational techniques
for such problems by
combining simulation techniques with the classical Galerkin method which
is widely used in
numerical analysis of partial differential equations and other problems in
physics and engineering. A
general description of this approach can be found in [4].
Practical applications of the convex optimisation techniques in risk
management require statistical
and econometric models of the underlying risk factors that affect the
investment and the liabilities of
a financial institution. Some of the models developed by our group are
reported in [2,6]. Applications
of the models and associated computational techniques to the Finnish
pension industry are reported
in articles [A,B] in Section 5 below.
The mathematical side of the research is based on earlier work of Teemu
Pennanen on
mathematical optimisation. The major part of it has been produced since
2008 by Pennanen at
King's College London.
The underpinning research is part of the general strategy of the
Financial Mathematics research
group in extending the applicability of mathematical finance. The strategy
is motivated by the well
documented failures of more traditional models of mathematical finance
during the recent financial
crises.
Key researchers
- Professor Teemu Pennanen
- King's College London since 10/2011
- Dr John Armstrong
- Lecturer, King's College London
- Dr Petri Hilli,
- QSA Quantitative Solvency Analysts Ltd
- Helena Aro,
- PhD student, Aalto University
References to the research
1*. T. Pennanen, Convex duality in optimal investment under illiquidity,
Mathematical Programming,
(2013). DOI:10.1007/s10107-013-0721-5.
2*. H. Aro, T. Pennanen, Stochastic modeling of mortality and financial
markets, Scandinavian
Actuarial Journal, 1-27, 2012. DOI:10.1080/03461238.2012.724442.
3. T. Pennanen, A.-P. Perkkiö, Stochastic programs without duality gaps,
Mathematical
Programming, 136:91-110, 2012. DOI: 10.1007/s10107-012-0552-9.
4*. T. Pennanen, Introduction to convex optimization in financial
markets, Mathematical
Programming, 134:157-186, 2012. DOI: 10.1007/s10107-012-0573-4.
5. T. Pennanen, Dual representation of superhedging costs in illiquid
markets, Mathematics and
Financial Economics, 5:233-248, 2012. DOI:
10.1007/s11579-012-0061-x.
6. P. Malo, T. Pennanen, Reduced form modeling of limit order markets, Quantitative
Finance,
12:1025-1036, 2012. DOI:10.1080/14697688.2011.589402.
Articles marked with an asterisk best indicate the quality of the
underpinning research.
Details of the impact
We have applied our risk management techniques to several financial
institutions in Finland
including the Ministry of Social Affairs and Health, the State Pension
Fund, and the Bank of Finland.
In the UK, we are developed an Asset-Liability Management (ALM) model for
the Pension Policy
Institute (PPI) to study the risks associated with variable annuity
pension contracts. Consultations
with the Ministry as well as with the Bank of Finland were initiated by
them, after they had heard
about our earlier work with pension insurers in Finland. Consultation with
the State Pension Fund
started after development of a pilot model of the state pension
liabilities. Collaboration with the PPI
was initiated when we contacted them and described our earlier work with
Finnish pension insurers.
Our consulting for the Ministry of Social Affairs and Health, the State
Pension Fund, and the Bank of
Finland was done through Quantitative Solvency Analysts (QSA), which is a
company founded by
Pennanen and his collaborators as a spin-off of their research projects.
The collaboration with the
PPI is a joint project aiming at developing computational tools for
quantifying long term uncertainties
in the UK pensions industry.
The models and computational techniques produced for the Ministry of
Social Affairs and Health
address the Finnish private sector pension system as a whole. Our models
build on the actual cash-flows
of both the assets and liabilities and it avoids many problems (most
notably pro-cyclicality)
associated with traditional accounting standards. The models' outputs have
led to many discoveries
concerning the financial risks of the pension system. The discoveries are
described in reports [A], [B]
and [C] the publication of which was funded by the Ministry. These reports
also include new
recommendations and guidelines for the financial risk management in
pension insurance companies
and in their regulation. The findings were widely recognised by the
pension industry and the media,
see for example [E,F,G,H].
Report [D] uses our asset-liability model to study how individual income
generated in the UK
automatic enrolment pension system compare to an income that might be
considered adequate in
an uncertain investment environment. Once automatic enrolment into
workplace pensions is fully
implemented in 2018, it is estimated that there could be between 6 and 9
million new savers into
workplace pensions. The simulation studies conducted with our model
suggest several possibilities
to improve the likelihood of achieving adequate retirement income [D].
The consultation provided for the State Pension Fund includes risk
analysis of their annual strategic
investment plan as well as a long term analysis of their funding ratio.
The modeling project started in
the fall of 2012, and some of the computational work is still under way.
The analyses have been
used by the management and the board of directors to asses financial risks
of the Fund. The funding
ratio is the key variable used in defining the targets of the State
Pension Fund set in Finnish law.
The ALM-based funding ratio is currently used in risk reporting together
with traditional actuarial
valuations. The analyses are based on models and computational techniques
developed by
Pennanen and his research team.
The consultation done for the Bank of Finland focused on the risk
analysis of the bank's reserves.
The work included the development of a stochastic model for the
investments of the bank as well as
a computational analysis of the bank's investment strategies. Our analysis
covered currency risk,
interest rate risk, and credit risk of the banking reserves in a dynamic
multiperiod setting. The results
produced by the models were used by the board of directors of the Bank in
the analysis of the
strategic investment plan.
Sources to corroborate the impact
Individual sources:
- Managing Director, State Pension Fund (testimonial received and
available on request)
- Director, Ministry of Social Affairs and Health, (testimonial received
and available on request)
Reports for practitioners:
A. P. Hilli, T. Pennanen, Eläkevakuuttaminen epävarmassa
sijoitusympäristössä, Unigrafia,
2012; this 94-page report describes the results of a research project
funded by the Ministry
of Social Affairs and Health (in Finnish, document available on request).
B. P. Hilli, T. Pennanen, Eläkevakuuttaminen epävarmassa
sijoitusympäristössä Laskelmia
työeläkkeiden rahastoinnin tehostamisesta, Aalto University, 2012;
this 50-page report
describes the results of a research project funded by the Ministry of
Social Affairs and Health
(in Finnish, document available on request).
C. P. Hilli, T. Pennanen, Työeläkkeiden rahastoinnin uudistamistarpeet, Työeläkelehti,
4, 2012;
invited article in Työeläkelehti, a magazine directed at experts in the
field of earnings-related
pension. It is published by the Finnish Centre for Pensions and comes out
five times per year
(in Finnish, document available on request).
D. J. Armstrong, L. Carrera, D. Redwood, T. Pennanen, What level of
pension contribution is
needed to obtain an adequate retirement income, Pension Policy Institute,
October 2013; full
report (ISBN 978-1-906284-27-5), and press release (documents available on
request).
Link to KCL-mirror
of PPI page for full report.
Articles in newspapers (in Finnish, documents available on request):
E. Tutkijat: Eläkelaitosten sijoitukset liian lyhytnäköisiä, Taloussanomat,
20/06/2012
F. Tutkijoiden hurja ehdotus: Suomeen vain yksi eläkelaitos, Taloussanomat,20/06/2012
Link to KCL-mirror
of the site.
G. Avoimuus tekisi hyvää eläkkeille, Helsingin Sanomat 28.12.2012
H. Raikas tuulahdus: Tutkijakaksikko ehdottaa mielenkiintoisia
uudistuksia eläkerahoitukseen
Suomen Kuvalehti 12.11.2012