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Stochastic Differential Games: 
An Application to Pension 
Funds under Adverse Selection 
Mario A. Garc┴a-Meza 
Jos└ Daniel L┏pez-Barrientos 
Magno Coloquio de Doctorantes en Econom┴a
Overview 
Adverse Selection 
Stochastic Differential 
Games 
An Application to 
Pension Funds: 
Separating Equilibrium 
Conclusions
ADVERSE SELECTION
Stochastic Differential Equations: Application to Pension Funds under Adverse Selection
STOCHASTIC 
DIFFERENTIAL 
GAMES
dx(t) = b(x(t), u1(t), u2(t))dt + (x(t))dW(t)
8i6= j, xi 2 Si : fi(x?i 
, x?j 
) $ fi(xi, x?j 
)
Stochastic Differential Equations: Application to Pension Funds under Adverse Selection
Lu1,u2?(x) := 
Xn 
i=1 
bi(x, u1, u2) 
@? 
@xi 
(x) + 
1 
2 
Xn 
i,j 
aij(x) 
@2? 
@xi@xj 
(x) 
dx(t) = b(x(t), u1(t), u2(t))dt + (x(t))dW(t)
rk(x, ?1,?2) := 
Z 
U2 
Z 
U1 
rk(x, u1, u2)?1(du1|x)?2(du2|x) 
J`T 
(x, ?1,?2) := E?1,?2 
x [ 
Z T 
0 
rk(x(t),?1,?2)dt] 
Jk(x, ?1,?2) := lim 
T!1 
sup 
1 
T 
Jk 
T (x, ?1,?2)
J1(??1,??2) ! J1(?1,??2) for every ?1 2 ?1 
J2(??1,??2) ! J2(??1,?2) for every ?2 2 ?2
Optimal Response 
?1 =  ̄I know ̄ 
?1 = silence 
?1 =  ̄Who doesn¨t? ̄ 
?1 =  ̄I love you too ̄ 
?1 =  ̄Thank you ̄ 
?1 =  ̄I love me too ̄ 
?2 =  ̄I love you ̄
Optimal Response 
J1(??1,?2) = sup 
?12?1 
J1(?1,?2) 
J2(?1,??2) = sup 
?22?2 
J2(?1,?2)
Optimal equations of 
Average Payoff 
J1 = r1(x, ??1,?2) + L??1,?2 
h1(x) 
= sup 
2?U 
1{r1(x, , ?2) + L,?2 
h1(x)} 
J2 = r2(x, ??1,??2) + L??1,?2?h2(x) 
= sup 
2?U 
2{r2(x, ??1, ) + L??1, h2(x)}
Stochastic Differential Equations: Application to Pension Funds under Adverse Selection
dx(t) = (μx(t) + u1(t)  u2(t))dt + dW(t) 
x(0) = x 
r1(x, u1, u2) = x 
r2(x, u1, u2) = u2 
Contribution Strategy 
u1, u2 2 [0, d] 
Withdrawal Strategy
J1= sup 
2P(U1) 
? 
x + (μx + !(x)  ?2(,|x))h01(x) + 
1 
2 
 
#2h00 1 (x) 
= sup 
[!(x)h01(x)] + [x(1 + μ)  ?2(,|x)]h01(x) + 
2P(U1) 
1 
2 
#2h00 1 (x) 
J2= sup 
2P(U2) 
? 
(x) + (μx + ?(,|x)  (x))h02(x) + 
1 
2 
 
#2h00 2 (x) 
= sup 
[ (x)(1  h02(x))] + (μx + ?1(,|x))h02(x) + 
2P(U2) 
1 
2 
#2h00 2 (x)
h01(x) 
1 1 1 
0 
0 
h02(x) 
(0(x), d(x)) (0(x), u(x)) (0(x), 0(x)) 
(d(x), d(x)) (d(x), u(x)) (d(x), 0(x))
h01(x) 
1 1 1 
0 
Contribute 
Nothing, Withdraw 
all possible 
Contribute 
nothing,withdraw 
arbitrary amount 
Contribute 
Living off my 
nothing, withdraw 
rents 
nothing 
0 
Contribute all 
possible,withdraw 
all possible 
Contribute all 
possible,withdraw 
arbitrary amount 
Contribute all 
possible,withdraw 
nothing 
h02(x) 
Abandon ship! 
New Money Buy and Hold
Stochastic Differential Equations: Application to Pension Funds under Adverse Selection
Conclusions 
An SDG with additive structure and average payoff can 
yield Nash equilibria with deterministic strategies that 
construct a separating equilibrium for pensions funds, 
thus solving the adverse selection problem 
This work can be extended still more by adding for 
example (1) The control set from fund manager(s), (2) 
The agent has to optimize through the selection of an 
optimal portfolio
References 
Pension Funds and Adverse Selection 
Akerlof (1970). The Market for ^lemons ̄: Quality uncertainty 
and the market mechanisms. The quarterly journal of 
economics, 488-500. 
Blake, D. (1999). Annuity markets: Problems and Solutions. 
Geneva Papers on Risk and Insurance. Issues and practice, 
358-375. 
Model for Stochastic Differential Game 
Escobedo-Trujillo, B. A., Lopez-Barrientos, J.D. (2014) 
Nonzero- Sum stochastic Differential Games with Additive 
structure and average payoff. Journal of Optimization Theory 
and Applications.

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Stochastic Differential Equations: Application to Pension Funds under Adverse Selection

  • 1. Stochastic Differential Games: An Application to Pension Funds under Adverse Selection Mario A. Garc┴a-Meza Jos└ Daniel L┏pez-Barrientos Magno Coloquio de Doctorantes en Econom┴a
  • 2. Overview Adverse Selection Stochastic Differential Games An Application to Pension Funds: Separating Equilibrium Conclusions
  • 6. dx(t) = b(x(t), u1(t), u2(t))dt + (x(t))dW(t)
  • 7. 8i6= j, xi 2 Si : fi(x?i , x?j ) $ fi(xi, x?j )
  • 9. Lu1,u2?(x) := Xn i=1 bi(x, u1, u2) @? @xi (x) + 1 2 Xn i,j aij(x) @2? @xi@xj (x) dx(t) = b(x(t), u1(t), u2(t))dt + (x(t))dW(t)
  • 10. rk(x, ?1,?2) := Z U2 Z U1 rk(x, u1, u2)?1(du1|x)?2(du2|x) J`T (x, ?1,?2) := E?1,?2 x [ Z T 0 rk(x(t),?1,?2)dt] Jk(x, ?1,?2) := lim T!1 sup 1 T Jk T (x, ?1,?2)
  • 11. J1(??1,??2) ! J1(?1,??2) for every ?1 2 ?1 J2(??1,??2) ! J2(??1,?2) for every ?2 2 ?2
  • 12. Optimal Response ?1 =  ̄I know ̄ ?1 = silence ?1 =  ̄Who doesn¨t? ̄ ?1 =  ̄I love you too ̄ ?1 =  ̄Thank you ̄ ?1 =  ̄I love me too ̄ ?2 =  ̄I love you ̄
  • 13. Optimal Response J1(??1,?2) = sup ?12?1 J1(?1,?2) J2(?1,??2) = sup ?22?2 J2(?1,?2)
  • 14. Optimal equations of Average Payoff J1 = r1(x, ??1,?2) + L??1,?2 h1(x) = sup 2?U 1{r1(x, , ?2) + L,?2 h1(x)} J2 = r2(x, ??1,??2) + L??1,?2?h2(x) = sup 2?U 2{r2(x, ??1, ) + L??1, h2(x)}
  • 16. dx(t) = (μx(t) + u1(t) u2(t))dt + dW(t) x(0) = x r1(x, u1, u2) = x r2(x, u1, u2) = u2 Contribution Strategy u1, u2 2 [0, d] Withdrawal Strategy
  • 17. J1= sup 2P(U1) ? x + (μx + !(x) ?2(,|x))h01(x) + 1 2 #2h00 1 (x) = sup [!(x)h01(x)] + [x(1 + μ) ?2(,|x)]h01(x) + 2P(U1) 1 2 #2h00 1 (x) J2= sup 2P(U2) ? (x) + (μx + ?(,|x) (x))h02(x) + 1 2 #2h00 2 (x) = sup [ (x)(1 h02(x))] + (μx + ?1(,|x))h02(x) + 2P(U2) 1 2 #2h00 2 (x)
  • 18. h01(x) 1 1 1 0 0 h02(x) (0(x), d(x)) (0(x), u(x)) (0(x), 0(x)) (d(x), d(x)) (d(x), u(x)) (d(x), 0(x))
  • 19. h01(x) 1 1 1 0 Contribute Nothing, Withdraw all possible Contribute nothing,withdraw arbitrary amount Contribute Living off my nothing, withdraw rents nothing 0 Contribute all possible,withdraw all possible Contribute all possible,withdraw arbitrary amount Contribute all possible,withdraw nothing h02(x) Abandon ship! New Money Buy and Hold
  • 21. Conclusions An SDG with additive structure and average payoff can yield Nash equilibria with deterministic strategies that construct a separating equilibrium for pensions funds, thus solving the adverse selection problem This work can be extended still more by adding for example (1) The control set from fund manager(s), (2) The agent has to optimize through the selection of an optimal portfolio
  • 22. References Pension Funds and Adverse Selection Akerlof (1970). The Market for ^lemons ̄: Quality uncertainty and the market mechanisms. The quarterly journal of economics, 488-500. Blake, D. (1999). Annuity markets: Problems and Solutions. Geneva Papers on Risk and Insurance. Issues and practice, 358-375. Model for Stochastic Differential Game Escobedo-Trujillo, B. A., Lopez-Barrientos, J.D. (2014) Nonzero- Sum stochastic Differential Games with Additive structure and average payoff. Journal of Optimization Theory and Applications.