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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Contributions to quantitative risk management in insurance Stphane Loisel ISFA, Universit Lyon 1 Habilitation diriger les recherches Stphane


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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes

Contributions to quantitative risk management in insurance

Stéphane Loisel

ISFA, Université Lyon 1

Habilitation à diriger les recherches

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 1 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Classical model

A recent correlation crisis in Kruger Park

Correlation between short-term mortality indicators can suddenly increase. Here correlation and the marginal risks increase at the same time. Another example: a drive with your mother-in-law.

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 4 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Classical model

Classical assumptions and our problem

Classical assumptions: R(t) = u + ct − N(t)

i=1 Xi

claim amounts (Xi)i≥1: sequence of i.i.d. r.v.’s, with finite mean, The (Xi)i≥1 are independent from (N(t))t≥0 (e.g. renewal process). Problem: Derive asymptotics of finite-time ruin probabilities for large risks ψ(u, t) = P(∃τ ∈ [0, t] , R(τ) < 0|R(0) = u), in more general models with dependence between claim amounts and possible correlation crises.

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 5 / 37

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Claims: dependent Pareto

  • Compound Poisson risk model ( τ ∼ Exp(λ))
  • Claims X ∼ Exp(Θ), where Θ ∼ Γ(α, β)

Ruin probability is Ψ(u) = λ/c 1 · βα Γ(α)θα−1e−βθdθ + ∞

λ/c

λ θc e−θue

λ c u

  • Ψθ(u)

· βα Γ(α)θα−1e−βθ

  • fΘ(θ), Θ∼Γ(α,β)

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Claims: dependent Pareto

Ψ(u) = 1 − Γ(α, βθ0) Γ(α) + β Γ(α)(βθ0)α−1e−βθ0 (u + β)−1

  • →u→∞0

Γ(α − 1, (β + u)θ0) ((β + u)θ0)α−2e−(β+u)θ0

  • →u→∞1

One can see that the probability of ruin decays to a constant lim

u→∞ Ψ(u) = 1 − Γ(α, βλ c )

Γ(α) > 0 as fast as u−1!! Compared to the independent case...

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Classical model

Some types of correlation (not developed in this talk)

Classical assumptions: R(t) = u + ct − N(t)

i=1 Xi

claim amounts (Xi)i≥1: sequence of i.i.d. r.v.’s, with finite mean, The (Xi)i≥1 are independent from (N(t))t≥0 (e.g. renewal process). Some models with embedded correlations: c is not constant over time and is adjusted to the observed previous claims (with Bühlmann linear credibility premium principle): impact of using credibility theory on the ruin probability (joint work with J. Trufin, 2009) dependence between the claim arrival process and the claim sizes (earthquake risk, flooding and drought risk, ...). Works of Boudreault et al. (2006), Albrecher et al. (2007), joint work with R. Biard, C. Lefèvre and H. Nagaraja (2010). dependence between claim arrivals and the intensity process: shot-noise processes, cycles influenced by large claims (joint work with

  • M. Bargès and X. Venel, 2009).

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 6 / 37

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Introduction Simple structure of dependence Dependence on the history of the process Our problems

Flooding-type risk process

Stéphane Loisel (ISFA, Lyon) A class of path-dependent claim amounts Istanbul 8 / 30

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Introduction Simple structure of dependence Dependence on the history of the process Our problems

Rewording flooding risk with simple ideas

Stéphane Loisel (ISFA, Lyon) A class of path-dependent claim amounts Istanbul 9 / 30

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Introduction Simple structure of dependence Dependence on the history of the process Our problems

Earthquake-type risk process

Stéphane Loisel (ISFA, Lyon) A class of path-dependent claim amounts Istanbul 10 / 30

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Introduction Simple structure of dependence Dependence on the history of the process Our problems

Rewording earthquake risk with simple ideas

Stéphane Loisel (ISFA, Lyon) A class of path-dependent claim amounts Istanbul 11 / 30

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Dependence between claim amounts

Impact of dependence between claim amounts

In practice, claim amounts are influenced by common factors. This leads to stochastic correlation models. This correlation may change during time, due to endogenous risk or external shocks (joint works with Wayne Fisher and Shaun Wang (2007) and with Pierre Arnal and Romain Durand (2010)), parameter uncertainty (see Meyers (1999)), ... What happens

◮ if dependence between claim amounts is governed by a Markovian

environment process?

◮ if claim amounts of different lines of business suddenly become more

dependent (in a common shock model)?

◮ if those correlation crises are triggered by some large claims?

Some useful references for sums of dependent risks: among others, Barbe et al. (2006), Albrecher et al. (2006), Kortschak and Albrecher (2008), Demarta (2002). Papers of Vladimir Kaishev and coauthors.

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 7 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Systemic risk

Systemic risk: securitization

Does securitization really atomize risk?

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 8 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Systemic risk

Systemic risk: securitization

Risk is just transferred and recombined, but does not disappear. If a large risk becomes reality, all counterparts may be affected and/or downgraded. Reinsurer’s default can lead to sudden increase in frequency and correlation

  • f claim amounts for the insurer. How to compute the ruin probability in

that case ? Work in progress with C. Blanchet, D. Dorobantu and S. Louhichi.

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 9 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Systemic risk

How can independent risks become suddenly strongly correlated?

Endogenous uncertainty: Uncertainty is generated/modified by response of individual entities to events Feedback loop: outcomes → forecasts → decisions → outcomes → revised forecasts → revised decisions → . . . (Millennium Bridge) Statistical relationships are endogenous to the model, and may undergo structural shifts (Goodhart’s Law: Any observed statistical regularity will tend to collapse once pressure is placed upon it for control purposes) Relevant when individual entities are similar in terms of forecasts and likely reactions to events Relevant when outcomes are sensitive to concerted actions

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 10 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Systemic risk

How can independent risks become suddenly strongly correlated?

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 11 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Systemic risk

How can independent risks become suddenly strongly correlated?

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 12 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Systemic risk

How can independent risks become suddenly strongly correlated?

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 13 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Systemic risk

Analogy with LTCM

This analogy is drawn from Danielsson and Shin (2003). Similar potential feedback loops for surrender risk in life insurance.

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 14 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Our framework in Biard et al. (2008)

Focus on some heavy-tailed distributions

Definition (Regular variation class (R))

F belongs to R−α, α ≥ 0 if and only if lim

x→∞

F(xy) F(x) = y −α for any y > 0. Note that if 0 < α < 1, any X with c.d.f. F has infinite mean.

Definition (Multivariate Regular variation class (MR))

A random vector X = (X1, ..., Xn) belongs to MR−α, α > 0 if and only if there exists a θ ∈ Sn−1, where Sn−1 is the unit sphere with respect to a norm |·|; such that P (|X| > tu, X/ |X| ∈ ·) P (|X| > u)

v

→ t−αPSn−1 (θ ∈ ·) , where

v

→ denotes vague convergence on Sn−1.

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 15 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Static dependence models

A basic situation

∀n ≥ 1, Xn = InW0 + (1 − In)Wn, where (Wn)n≥0 : i.i.d. sequence, common cdf FW ∈ R−α, α ≥ 0, (In)n≥1 is a sequence of i.i.d Bernoulli random variables, with P(I1 = 1) = p ∈ [0, 1], The Wn, n ≥ 0 are independent from the Ik, k ≥ 1. Denote the aggregate claim amount (with Sp

t = 0, if Nt = 0) by

Sp

t = N(t)

  • k=1

Xk. First, we calculate P(Sp

t > x) for large x, then we approximate ψp(u, t) by

P(Sp

t > u) and, finally, we compare ψp(u, t) and ψq(u, t) for 0 ≤ p < q ≤ 1.

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 16 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Static dependence models

Important properties and consequences

Max-sum property: if F1 and F2 belong to R−α, α > 0 then F1 ∗ F2(x) ∼ F1(x) + F2(x) for large x, Convolution closure: if F1 and F2 belong to R−α, α > 0 then so does F1 ∗ F2. Since FW belongs to R−α, for any k ≥ 1, 1 ≤ j ≤ k − 1 and any pairwise distinct n1, ..., nk−j ≥ 1, for large x, P

  • Wn1 + ... + Wnk−j + jW0 > x

(k − j)FW (x) + FW x j

 k − j + FW

  • x

j

  • FW (x)

  FW (x) ∼ (k − j + jα)FW (x) (1)

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 17 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Static dependence models

P(Sp(t) > x) ∼   

  • k=1

e−λt (λt)k k!  

k

  • j=0

k j

  • pj(1 − p)k−j (k − j + jα)

     FW (x). (2) can be rewritten as P[Sp(t) > x] ∼ {λt + E [(Z p(t))α − Z p(t)]} FW (x), (3) where Z p(t) denotes a binomial random variable Bin[N(t), p]. The mixed binomial law MBin[N(t), p] is stochastically increasing in p (see, e.g., Lefèvre and Utev (1996)). Since the function f (x) = xα − x, x ∈ {0, 1, . . .}, is decreasing (resp. increasing) when α < 1 (resp. α > 1), we get (for u large enough), for α < 1 (infinite mean case), 0 ≤ p < q ≤ 1 ⇒ ψp(u, t) > ψq(u, t), and for α > 1 (finite mean case), 0 ≤ p < q ≤ 1 ⇒ ψp(u, t) < ψq(u, t).

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 18 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Dependence between claim amounts influenced by an environment process

Correlation crises

Dependence between claim amounts, claim size distribution and intensity are modulated by a Markovian environment process. Markov environment process (J(t))t≥0 with J ≥ 2 states 1, . . . , J

◮ with initial distribution π0 ◮ and transition rate matrix Q.

Claim amounts: for 1 ≤ i ≤ n, sequence of i.d. random vectors (X i

m)m≥1 s.t.

∀n ≥ 1, X i

n = I i nW i 0 + (1 − I i n)W i n,

◮ where the (W i

n)n≥0 are i.i.d. r.v.’s with cdf F i W ∈ R−αi ,

◮ the (I i

n)n≥1 are i.i.d. Bernoulli r.v.’s with parameter pi ∈ [0, 1],

◮ the W i

n, n ≥ 0 are independent from the I i k, k ≥ 1

◮ and the W i

n, n ≥ 0 and I i k, k ≥ 1 are independent from a Poisson

process Ni(t) with parameter λi. Define the J independent processes (1 ≤ i ≤ J) as Y i(t) = cit −

Ni (t)

  • mi =1

X i

mi

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 19 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Dependence between claim amounts influenced by an environment process

Correlation crisis

Let Tp be the instant of the pth jump of the process Jt, and define (R(t))t≥0 by R(t) = u +

  • p≥1
  • 1≤i≤n

(Y i(Tp) − Y i(Tp−1))1{JTp−1=i,Tp≤t} +

  • p≥1
  • 1≤i≤n

(Y i(t) − Y i(Tp−1))1{JTp−1=i,Tp−1≤t<Tp}. A typical modulated risk process with two states (red and blue).

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 20 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Dependence between claim amounts influenced by an environment process

Correlation crises: case where α1 < αi for all i ≥ 2

Theorem

As u → +∞, we have for any t > 0 ψ(u, t) ∼ J

  • i=1

π0(i)E

  • M⊥

i +

  • [Mcom

i

]α1 ¯ F 1(u), where W 1

i (t) is the time spent by the environment process in state 1 during

[0, t] given that J(0) = i, M⊥

i

follows a mixed Poisson distribution with random parameter λ1(1 − p1)W 1

i (t),

and Mcom

i

follows a mixed Poisson distribution with random parameter λ1p1W 1

i (t).

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 21 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Dependence between claim amounts influenced by an environment process

Correlation crises: case where α1 < αi for all i ≥ 2

Theorem

If besides α1 ∈ N, we have E

  • M⊥

i

  • = λ1(1 − p1)E
  • W 1

i (t)

  • = λ1(1 − p1)D1

i (1, t),

and E

  • [Mcom

i

]α1 = E  

α1

  • k=0

S(α1, k)(λ1p1)k W 1

i (t)

k   =

α1

  • k=0

S(α1, k)(λ1p1)kD1

i (k, t),

where S(α1, k) is the (α1, k) Stirling number of the second kind, and where for m ≥ 1, D1

i (m, t) = E

  • W 1

i (t)

m | J(0) = i

  • Castella et al. (2007)

is the ith component of vector D1(m, t) defined by D1(0, t) = 1 and for m ≥ 1, D1(m, t) = r t eQ(t−u)A11D1(m − 1, u)du where A11 is J × J with coeff. δi1δj1.

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 22 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Dependence between claim amounts influenced by an environment process

Pure correlation crises: case where αi = α ∈ N \ {0} for all 1 ≤ i ≤ 3

Assume that in state 1, the W 1

n , n ≥ 1 are i.i.d.,

in state 2, there is a light correlation: the W 2

n , n ≥ 1 have Gaussian copulas,

and in state 3, the W 3

n , n ≥ 1 are given by the basic dependence model with

parameter p3. Then,

Theorem

We have for any t > 0, as u → +∞, ψ(u, t) ∼ 3

  • i=1

π0(i)[λ1D1

i (1, t) + λ2D2 i (1, t)

+λ3 1 − p3 D3

i (1, t) + α

  • k=0

S(α3, k)(λ3p3)kD3

i (k, t)]

  • ¯

F(u). Similar results may be obtained with classical copulas, and dependence between different state processes. See Biard, Lefèvre and L. (2008) for further details.

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 23 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes

1

Ruin and correlation

2

Optimal reserve allocation Optimal allocation problem Heavy-tailed case Light-tailed case

3

Sensitivity and robustness

4

New themes

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 24 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Optimal allocation problem

The allocation problem is the minimization of the risk measure IT (u1, u2) = E

  • I 1

T (u1)

  • + E
  • I 2

T (u2)

  • ,

for u1 ≥ 0 and u2 ≥ 0 under the constraint u1 + u2 = u for large u where I i

T (ui) = T

  • 1{Ri (t)<0}|Ri(t)|dt

i = 1, 2.

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 25 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Heavy-tailed case

Heavy-tailed case and T = ∞

No environment process. FW1 ∈ R−α1 and FW2 ∈ R−α2 with α1 < α2.

Theorem

If we denote u1 = (1 − β(u))u and u2 = β(u)u with β(u) ∈ (0, 1) we have for large u β(u) ∼

  • D

2

D

1

FW2(u) FW1(u) 1/(α2−2) , where for i = 1, 2, D

i = (αi − 3)−1 1

ci 1 1 − ψi(0) λi + λ c − (λi + λ)µi 1 (αi − 1)(αi − 2)(αi − 3). The finite-time case can also be treated (see Biard, Macci, L. and Veraverbeke (2010) for details).

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 26 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Light-tailed case

Light-tailed case and T = ∞

No environment process. We assume that the Cramer-Lundberg exponent exists for each process and is equal to Ri, i = 1, 2 with R1 < R2.

Theorem

For large u, the solution is given by u1 = R2 R1 + R2 u + 1 R1 + R2 log

  • M

2

M

1

  • + o(1),

u2 = u − u1 + o(1), where M

i = −Ri

1 ci 1 1 − ψi(0) 1 − (λi + λ)µi R2

i ((λi + λ) ˆ

FWi

(Ri) − 1) i = 1, 2. Other allocation problems could be considered (see Cénac et al. (2010)).

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 27 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes

1

Ruin and correlation

2

Optimal reserve allocation

3

Sensitivity and robustness Robustness analysis and ERSM Sensitivity analysis of finite-time ruin probabilities

4

New themes

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 28 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Robustness analysis and ERSM

Motivation

500 1000 1500 2000 2500 3000 3500 4000 0,025 0,03 0,035 0,04 0,045 0,05 Q95

For initial reserve u ≥ 0 (see L., Mazza and Rullière (2008, 2009)), we show the convergence (in distribution) of the renormalized difference √ N

  • ¯

ψ(u, t) − ¯ ψN(u, t)

  • between the classical finite-time non-ruin probability ¯

ψ(u, t) and its equivalent obtained when claims are drawn from the empirical distribution

  • f a sample of size N towards a centered Gaussian random variable. The

asymptotic variance can be obtained from easy-to-simulate quantities, thanks to so-called partly shifted processes.

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 29 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Robustness analysis and ERSM

OM (or partly shifted) risk processes

Offset-modified or partly shifted risk process (link with Rama Cont’s vertical derivative)

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 30 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Robustness analysis and ERSM

Reliable ruin probability

Set φY (u, t) = P

  • RY

s ≥ 0 ∀s < t | RY 0 = u

  • ,

where RY

s = Rs − 1{U<s}Y , s ≥ 0, and U is uniform on [0, t]. U, Y and

(Rt)t≥0 are mutually independent. Then the variance of the ruin probability is Var

  • λtφY (u, t)
  • .

As Takács’s lemma remains valid for partly shifted processes, those computations can be done quite quickly.

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 31 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Robustness analysis and ERSM

Estimation Risk Solvency Margin (ERSM)

10 10.5 11 11.5 12 12.5 13 13.5 14 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 ERSM

If uη and uη,ε are respectively defined as the initial capital required to ensure that ψ(uη, t) ≤ η and ψN,reliable

1−ε

(uη,ε, t) ≤ η, the Estimation Risk Solvency Capital ERSMη,1−ε can be defined as the additional capital needed to take estimation risk into account : ERSMη,1−ε = uη,ε − uη. Other estimators may also be used (see Susan Pitts’s recent work).

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 32 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Sensitivity analysis of finite-time ruin probabilities

Sensitivity analysis

Because C 2 condition is not satisfied, Malliavin calculus on the Poisson space (see Privault and Wei, 2004) cannot be used. We had to use integration by parts to compute the sensitivity of the finite-time ruin probability w.r.t. initial reserve u ≥ 0 (joint work with Nicolas Privault (2009)).

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 33 / 37

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes

1

Ruin and correlation

2

Optimal reserve allocation

3

Sensitivity and robustness

4

New themes Longevity risk Other perspectives

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 34 / 37

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Introduction Characteristics of longevity risk Modeling longevity risk Longevity risk and new regulations Transferring longevity risk Modeling issues for pricing Basis Risk Detection of drift changes

FIGURE: Migrations and life expectation

4/ 57 Stéphane Loisel, ISFA- U. Lyon 1 Longevity Risk

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French national population

1/29

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Kappa(t) in the Lee-Carter model (French nat. pop.)

2/29

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Longevity improvements at different ages

3/29

Examining Structural Shifts in Mortality Using the Lee-Carter Method Lawrence R. Carter, Alexia Prskawetz

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Introduction Characteristics of longevity risk Modeling longevity risk Detection of drift changes Longevity and mortality risks: a natural hedge? Transferring longevity risk Modeling issues for pricing

PURE LONGEVITY RISK

change of the average trend short-term oscillations around the average trend (risk of over-reactions) Heterogeneity and basis risk : the evolution of the policyholders mortality is usually different from that of the national population (selection effects). Financial Risk Long term interest rate risk Counterparty risk

6/ 40 Stéphane Loisel, ISFA- U. Lyon 1 Longevity Risk

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Ruin and correlation Optimal reserve allocation Sensitivity and robustness New themes Other perspectives

Other perspectives

s-convex extrema for t-monotone distributions in ruin theory (univariate and multivariate issues) about variable annuities Climate change risk and actuarial science (MIRACCLE project) Enterprise Risk Management Solvency II; accelerating nested simulations Value of insurance portfolios

Stéphane Loisel (ISFA, Lyon) QRM in insurance November 2010 36 / 37

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Correlations and correlation crises in risk theory

St´ ephane Loisel

ISFA, Universit´ e Lyon 1

Montr´ eal, Nov. 2011 With H. Albrecher and C. Constantinescu

http://dx.doi.org/10.1016/j.insmatheco.2010.11.007

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1

La méthodologie SdS

Le capital économique (suite)

  • Le capital économique Solvency II correspond au montant de fonds propres dont

doit disposer la compagnie pour faire face à une ruine économique à horizon 1 an et au niveau 99,5%.

  • Trois notions fondamentales :

− Ruine économique = situation où la valeur de marché l’actif est inférieure à la fair value des passifs − L’horizon d’une année impose de pouvoir disposer de la distribution des fonds propres économiques dans un an − Le niveau 99,5% permet de garantir la solvabilité de la compagnie. La probabilité de l’événement « ruine économique » est dans ce cas inférieure à 0,5%.

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2

La méthodologie SdS

Principe de la méthode

  • Objectif d’un calcul SdS : calcul du quantile à 0,5% de la distribution de FP de fin de

première période

  • Remarque : pour un run basé sur 5000 simulations primaires, on retient la 25ième « pire

valeur » de la distribution de FP1

Il n’est donc pas nécessaire de disposer de toute la distribution de FP1

2

t=0 t=1

Temps

Scenario 1 Scenario i Scenario N

Scenario 1 Scenario j Scenario M

Scenario 1 Scenario j Scenario M (issu du scenario 1) (issu du scenario N)

Simulations Primaires « Monde Réel » Simulations secondaires « market consistent » issues des simulations primaires

A1

1 FP1 1

VEP1

1

Bilan en t=1 - Scenario 1

A1

N

FP1

N

VEP1

N

… …

t=T

A0 FP0 VEP0

Bilan en t=0

Bilan en t=1 - Scenario N

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3

Idées clés

Principe de la méthode

  • Principe : Construction d’un automate de décision « accélérateur SdS » qui,

par l’intermédiaire de facteurs de risque, calcule les scénarios les plus adverses en termes de solvabilité

  • > sans effectuer un jeu complet de simulations
  • 4
  • 3
  • 2
  • 1

1 2 3 4

  • 4
  • 3
  • 2
  • 1

1 2 3 4

Stock ZC

  • 4
  • 3
  • 2
  • 1

1 2 3 4

  • 4
  • 3
  • 2
  • 1

1 2 3 4 <0,5% 0,5% - 5% 5% - 10% >10%

Approche « SdS exhaustif »

  • Tous les scénarios sont calculés-

Action

Approche « Accélérateur SdS »

  • Calcul des scénarios sélectionnés-

Région à explorer

(Région où les scénarios sont les plus adverses en terme de solvabilité) Chaque simulation primaire est caractérisée par un couple de facteurs de risque Action x ZC ZC

slide-49
SLIDE 49

4

  • Itération 1 : a1 = 2.73

L’accélérateur SdS initial

Mise en œuvre (1/3)

Rang FP1 1

  • 1153

2

  • 1099

3

  • 883

4

  • 843

5

  • 837

6

  • 758

7

  • 744

8

  • 724

9

  • 714

10

  • 712

11

  • 696

12

  • 673

13

  • 653

14

  • 647

15

  • 614

16

  • 487

17

  • 466

18

  • 462

19

  • 438

20

  • 388

21

  • 350

22

  • 344

23

  • 339

24

  • 295

25

  • 191

V1=

  • 4
  • 3
  • 2
  • 1

1 2 3 4

  • 4
  • 3
  • 2
  • 1

1 2 3 4

slide-50
SLIDE 50

5

L’accélérateur SdS initial

Mise en œuvre (2/3)

  • Itération 2 : a2 = 2.45

V2=

Rang FP1 1

  • 1153

2

  • 1099

3

  • 883

4

  • 843

5

  • 837

6

  • 758

7

  • 744

8

  • 724

9

  • 714

10

  • 712

11

  • 696

12

  • 673

13

  • 653

14

  • 647

15

  • 614

16

  • 487

17

  • 466

18

  • 462

19

  • 458

20

  • 438

21

  • 423

22

  • 388

23

  • 377

24

  • 350

25

  • 344
  • 4
  • 3
  • 2
  • 1

1 2 3 4

  • 4
  • 3
  • 2
  • 1

1 2 3 4

slide-51
SLIDE 51

6

L’accélérateur SdS initial

Mise en œuvre (3/3) Itération 3 : a3 = 2.30

V3=V2=

Arrêt de l’algorithme

Nombre de simulations effectuées = 300

Rang FP1 1

  • 1153

2

  • 1099

3

  • 883

4

  • 843

5

  • 837

6

  • 758

7

  • 744

8

  • 724

9

  • 714

10

  • 712

11

  • 696

12

  • 673

13

  • 653

14

  • 647

15

  • 614

16

  • 487

17

  • 466

18

  • 462

19

  • 458

20

  • 438

21

  • 423

22

  • 388

23

  • 377

24

  • 350

25

  • 344
  • 4
  • 3
  • 2
  • 1

1 2 3 4

  • 4
  • 3
  • 2
  • 1

1 2 3 4

slide-52
SLIDE 52

7

Evidemment il faudrait beaucoup plus que 5000 simulations primaires! Intervalles de confiance asymptotiques

  • btenus à l’aide de techniques de processus

empiriques

May 3, 2012

slide-53
SLIDE 53

8

Risque de piégeage de l’algorithme

  • Si je pense avoir bien sélectionné mes facteurs de risque mais qu’en

fait je me trompe complètement sur la forme de la fonction NAV, l’algorithme risque-t-il de converger rapidement vers une mauvaise valeur (piégeage) ?

  • Dans le cas où on n’a aucune information sur la situation nette et on

choisit les séries de 100 points (sur 5000 au total) sans remise au hasard, la probabilité de piégeage – au 2ème tirage est environ de 5,363 .10-9 – avant le 6ème tirage est inférieure à 0,323%

  • La probabilité de piégeage avec sélection d’une VaR empirique de

niveau inférieur à 99% avant le 10ème tirage est inférieure à 0,448%

  • Si l’algorithme met du temps à converger, regarder comment les 50

pires valeurs ont évolué donne des renseignements sur la crédibilité du résultat obtenu.

May 3, 2012

slide-54
SLIDE 54

Types of guarantees offered in Variable Annuities Risk analysis and Solvency II pitfalls Confronting points of view of insu Guarantees and surrender risk

GMWB

Stéphane Loisel (ISFA, Lyon) Variable annuities

  • Dec. 2nd, 2010

11 / 27

slide-55
SLIDE 55

9

Justification et algorithme de vérification

  • Une fonction concave sur un ensemble convexe compact atteint

son minimum en l’un de ses points extrémaux (conséquences du Th. De Krein-Millman)

  • Algorithme de vérification dans le cas concave
  • Faisabilité en dimensions 3, 4, …
  • http://www.cse.unsw.edu.au/~lambert/java/3d/hull.html
  • Et dans les autres cas?

May 3, 2012

slide-56
SLIDE 56

10

On peut utiliser des polygônes « entre deux cercles »

May 3, 2012

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SLIDE 57

11

Un cas où ca ne marche pas directement (facteur(s) en trop, à éliminer d’abord)

May 3, 2012

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SLIDE 58

12

Facteurs de risque à queues de distribution plus lourdes

May 3, 2012

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SLIDE 59

13

Quelques références (non exhaustives)

  • L. Devineau, S. Loisel, Risk aggregation in Solvency II: How to

converge the approaches of the internal models and those of the standard formula?, Bulletin Français d'Actuariat, No 18, Vol. 9, 107- 145 (2009).

  • L. Devineau, S. Loisel, Construction d'un algorithme d'accélération

de la méthode des ''simulations dans les simulations'' pour le calcul du capital économique Solvabilité II, Bulletin Français d'Actuariat (BFA), No. 17, Vol. 10, 188-221 (2009).

  • M. Chauvigny, L. Devineau, S. Loisel, V. Maume-Deschamps

Accelerating nested simulations in Solvency II: theory and practice in a copula and distribution-free framework, http://hal.archives-ouvertes.fr/hal-00517766 Voir les références dans le papier en suivant le lien ci-dessus.

May 3, 2012

slide-60
SLIDE 60

14

Quantiles géométriques

May 3, 2012