Θεωρία Κινδύνου
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1
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2009
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2
, .
, , .
, , , .
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3
1.
2.
1:
1.
1.1
1.2
1.3
1.3.1 VaR
1.3.2 (Expected Shortfall)
1.4
1.4.1
1.4.2 VaR
1.4.3
2:
2.1 (Market Risk)
2.1.1 -
2.1.2
2.1.3 Monte Carlo
2.2 (Operational Risk)
2.2.1
2.2.1.1 (BI)
2.2.1.2
2.2.2
3: (Credit Risk)
3.1
3.1.1 Merton
3.1.2 Merton
3.1.3
3.1.4
3.1.5
3.1.6 KMW
3.1.7
3.1.8
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4
3.2
3.2.1
3.2.2
3.3
3.3.1 Bernoulli
3.3.2 Poisson
3.3.3
3.3.4
3.4 Monte-Carlo
3.4.1
3.4.2 Bernoulli
3.4.3 Bernoulli
4:
4.1
4.1.1 VaR
4.2
4.2.1
4.2.2 Euler
4.2.3 Euler
5:
5.1 Fsn
5.2 Poisson
5.3 -
5.4 Panjer
5.5 Poisson
5.6 Poisson
5.7 Poisson
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5
1.
20 . 1950
.
Hanry Markowitz 1952
. ,
-
.
1970.
:
i)
.
ii)
.
2.
1970 1988
(Bassel I).
:
.
,
.
. 2001 ,
(Bassel I), .
, ,
:
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6
i) : .
ii) : .
iii) : .
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7
1 :
1.
1.1
(, F, P)
.
1.1: ,
S
V(s).
1.2:
[S, S+] :
SSss VVL , ,
.
1.3: ssL ,
.
,
.
,tY t tYY1 .
ttttt VVLL 11,1
tZttFV , (1.1),
t d- dtt ZZ ,1, ,..., ,
F dx .
(1.1) .
,tX t
1ttt ZZX ,
ttt ZtXZttFFL ,),1(1 1
-
8
1.4: t d
tt ZtXZttFFx ,),1( , dx
)( 11 ttt XL .
F , -
d
iittZttt XZtfZtFL i
1
,11 ),(,
L - .
1.5: :
d
i
itZttt XZtfZtFx i1
),(,
.
-
9
1.2
.
.
1tL t
F F
tF - Boole. :t sx s tF , -
Boole
(). 1tx t
F F 1tx
tF .
1tL t
F F :
11 1( ) ( )
t tt t t tL F tF P x P L F
1tL
F
xF d . ,tX t
.
1 1 1( ) ( )
tL t ttF P x P L
,
.
-
10
1.3
.
:
)
)
)
) .
. -- (VR)
(Expected Shortfall).
1.3.1. VR
--
.
, :
( ) ( )LF P L (1.3.1)
LF
.
:
: ( ) 1LinF F
LF
.
1.3.1 (--).
0,1 . -- ,
,
L (1-).
: ( ) 1 : ( )LV R inF P L inF F (1.3.2)
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11
0,95 0,99 1 10
.
VR
(1-).
VR .
1.3.2 ( )
i) :T ,
T :
( ) : ( )T y inF x T x y
.
ii) F , F
F .
0,1 - F
: ( )q F F inF x F x
1.3.1 0x - F
:
i) 0( )F x ii) ( )F x
1.3.2. (Expected Shortfall)
1.3.2 ( ). L E L
LF ,
0,1 :
11
1 u LES q F du (1.3.2)
( )u L Lq F F u LF .
:
11
1 uES V R L du
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12
, VR
u .
ES L . ES V R .
1.3.2 L
LF 0,1 , :
( ; ( ))( )
1
E L L q LES E L L V R (1.3.3)
( ; ) ( )AE X A E XI
X .
1: LF (1.3.3)
:
1( ; ) (1 )
1ES E L L q q P L q (1.3.4)
1.3.3 i iL
LF :
1
,
1lim[ (1 )]
n
i ni
n
L
ESn
(1.3.5)
1, ,n n nL L 1, , nL L [ (1 )]n
(1 )n .
ES
VR. ,
VR.
.
-
13
1.4
(coherent risk)
1.4.1
(, F, P) .
L0 (, F, P) (, F)
.
L0 (, F, P)
.
.
) L1 L2 , L1+L2
) L1 L1 >0
: R.
(L)
L,
.
(L) 0 .
: R
, :
1 ( ) L
(L+) = (L)+
2 () L1, L2 (L1+L2) (L1) + (L2)
3 ( ) L >0 (L) = (L)
4 () L1, L2 L1L2, (L1) (L2)
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14
1.4.1 ( )
,
, ( ) .
1.4.2 VR
d=100 .
.
(2%).
100 .
, 1t 105,
.
Li i-, 100 -5
i i-.
i 1 [ , 1]t t
.
Li = 100Yi -5(1 - Yi) = 105 Yi 5
Li
P(Li = -5) = 0.98 P(Li = 100) =0.02.
. 10.000.
100 100 .
.
VR.
VR 95%
.
: LA = 100L1 VR0.95(LA) = 100VR0.95(L1)
P(L1-5) = 0.98 0.95 P(L11) = 0 < 0.95 l
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15
VR0.95(LA) = -500
500
VR
95%.
. 100 100
1 1
105 500B i iIi Ii
L L Y
100
1
( ) 105 500a B a iIi
VaR L q Y
100
1
B (100, 0.02)ii
M Y
P(M5) 0.984 0.95 P(M4) = 0.949 < 0.95
0.95( ) 5q M
0.95( ) 25BVaR L .
125
VR 95%.
.
.
VR .
, :
100 100
1 11 1
( ) 100 ( ) (100 )i ii i
P L P L P L P L
, ,
.
--
.
1.4.2 ( VR
)
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16
X ~ Ed (,,)
01
: , d
i i ii
M L L X R
L1, L2 M 0.5 < 1
1 2 1 2( ) ( ) ( )V R L L V R L V R L
1.4.3
1.4.3. .
: ,
11
( )1
ES V R L duu
.
:
L1, , L1 L1,n
Ln,n m 1 m n :
1, 11
sup : 1 i ...m
m
i n i i mi
L L L i m
L L F
1 1( , ), . . . , ( , )
n nL L L L F.
( , ) + i i iL L L L ,( + ) i nL L 1( + ) , , ( + ) nL L L L :
1, 11
( ) sup ( ) ... ( ) : 1 ...m
m
i n i i mi
L L L L L L i i m
1 1
sup ... : 1 ...mi i m
L L i i m
1 1sup ... : 1 ...
mi i mL L i i m
, ,1 1
m m
i n i ni i
L L
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17
m = n(1-) n, ( ) ( ) ( )ES L L ES L ES L
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18
2 :
2.1. (Market risk)
(.. ,
, , ) .
.
2.1.1
1tX
:
1 ( , )t dX N
.
1 [ ] 1( )t t tL X .
:
[ ]( ) ( )t t tx c b x (2.1.1)
tc tb
t.
1tX .
:
1 [ ] 1( ) ( , )t t t t t t tL X N c b b b (2.1.2)
,
1, ,t n tX X .
,
-
-
19
.
1 1 1( , )t t d t tX F N
1t 1t - .
.
. ,
.
2.1.2
.
[ ] 1( )t tL X
1, ,t n tX X . ,
.
[ ]( : 1,...,s t sL X s t n t (2.1.2)
sL
s.
.
xF
xF .
1, ,t n tL L
[ ]( )t X xF .
.
.
-
20
2.1.3 Monte-Carlo
1, ,t n tX X .
.
m-
, :
(1) ( )1 1, ,
mt tX X
:
( ) ( )1 [ ] 1( : 1,...,
i it t tL X i m
1tX ,
.
-
21
2.2. (Operational Risk)
, (, )
.
2.2.1
:
i) () ii) .
2.2.1.1 ()
,
.
,
.
t
:
3
1
1( ) max( ,0)t t iBI
t i
RC OR IZ
3
01
t it Ii
Z I
t iI t i
15% .
2.2.1.2
8 :
, , ,
, , , ,
.
-
22
.
:
3 8
1 1
1( ) max ,0
3
t t is j j
i i
RC OR I
, t i
j
.
.
2.2.2
,
: ,
, , -
, ,
, -
.
t.
:
, . , ,: 1,..., ; 1,...,8; 1,...,7; 1,...,t i b t i bX i T b N
, .t i bX -
b t i .
, ,t i bN :
T : ( 5T )
-
23
b
t i :
, ,7, , ,
1 1
t i bNt i b t i b
k
L X
t i :
, ,8,
1 1
t i bNt i t i b
k
L L
tL t
VR
.
( ) ,
:
( )t tAMRC OR L
= 0,99 -0,999.
,
:
8,
1
( )t t bAMb
RC OR L .
-
24
3 : (Credit Risk)
.
,
, .
-.
Merton (1974),
,
.
,
.
. -
.
-.
-
25
3.1
.
. ( tX )
tX
0t .
3.1.1 Merton
tV
.
Merton :
T. t
St Bt . (
).
.
Vt=St + Bt, 0 t T .
,
.
:
i) TV B ,
.
St = Vt B.
.
ii) TV B ,
. ,
-
26
.
, T TB V , ST = 0.
:
max ,0T T TS V B V B (3.1)
min ,T T TB V B B B V (3.2)
Merton (Vt) Brown
:
t t t tdV V dt V dW
, 0 Brown ( tW ).
20
1exp
2T TV V T W
2 20
1ln ln ,
2TV N V T T
:
20
1ln( / )
2ln lnT T
B V T
P V B P V BT (3.4)
.
3.1.2 Merton
Merton
Vt
.
(3.1.1)
i)
ii) 0
-
27
iii)
.
Th V , (3.1)
(3.2) (3.1.1).
( , )tF t V
t T .
. F(t,Vt) (PDE)
F(t,u) :
2 21, , , ,2
t y uu uF t u u F t u ruF t u rF t u 0,t T (3.5)
f(t,u)=h().
(3.5) Black- Scholes.
. F(t,Vt) Q
( , )tF t V
Q. Q Vt
:
t t t tdV V dt V dW (3.3)
W W Q Brown (
).
:
( )( )( , ) T
Q r T tt V tF t V E e h F (3.6)
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28
3.1.3
PDE (3.5)
(3.6) Black-Scholes CBS.
t :
( )
,1 ,2
2
,1 ,2 ,1
( , ; , , , ) ( ) ( )
1ln ln ( )
2
BS r T tt t v t t t
T v
t t t v
v
S C t V r B T V d Be d
V B r T t
d d d T tT t
(3.7)
2 201
ln (ln , )2T v v
V N V r T T
t=0 , :
2
0
0,2 0,2
1ln ln
2( ) 1 ( )
T v
T
v
V V r T
Q V B Q d dT
(d)=1-(-d) 1-(d0,2) .
1-(dt,2)
t.
3.1.4
(ii) (3.11) -
tT
0( , ) exp( ( ))t T r T t
(3.2) :
0( , ) ( , ; , , , )BS
t t vB B t T P t V r B T (3.8)
-
29
( , ; , , , )BS t vP t V r B T Black-Scholes strike B
( )tV r .
( )
,2 ,1( , ; , , , ) ( ) ( )BS r T t
t v t t tP t V r B T Be d V d (3.9)
,1td ,2td (3.7).
(3.8) (3.9) :
0 ,2 ,1( , ) ( ) ( )t t t tB t T B d V d (3.10)
3.1.5
(3.10)
C(t,T). -
P0(t,T) P1(t,T)
.
11 0
0
( , )1 1( , ) ln ( , ) ln ( , ) ln
( , )
P t TC t T t T T t
T t T t P t T (3.11)
Merton 11
( , ) tP t T BB,
,2 ,1
0
1( , ) ln ( ) ( )
( , )t
t t
VC t T d d
T t B t T (3.12)
20( , ) 1ln ( )2
( ,1)v
t
v
B t TT t
Vd t
T t dt,2
-
30
T-t, C(t,T) v
0( , )
t
B t Td
V.
3.1.6 KMV
Merton
KMV 1990.
KMV .
KMV
EDF. EDF
KMV.
(3.4) =1 (d)=1-(-d)
2
0
1ln ln
21
v v
Merton
v
V B
EDF (3.13)
KMV EDF Merton.
Merton
.
(3.13).
(DD)
0
0
( )
v
V BDD
V (3.14)
B V0 .
3.1.7
.
-
31
:
, :
Table 8.2: Probabilities of migrating from one rating quality to another within one year.
Source: Standard & Poors CreditWeek (15 April 1996)
.
, S&P
.
, CCC
.
[0,]. ( ), 0 j np j
.
j
. (0)p
.
t v t v t tdV V dt V dW
-
32
20
1exp
2T v v v TV V T W
.
0 1 1... n nd d d d
1( ) ( )j T jP d V d P j {0,..., }j n .
.
1d .
VT jd .
:
2
0
1ln ln
2T v v
T
v
V V T
XT
20
1ln ln
2j v v
j
v
d V T
dT
j 1j T jd X d .
3.1.8
.
Merton.
m-
Vt Vt = (Vt,1,, Vt,m)
-
33
m- Brown v = (v1,, vm)
v = (v1,, vm) .
i VT,I
2
0
1exp
2T v v v TV V T W
v= vi , v= vi WT=WTi
H WT=(WT,1,WT,m) WT~Nm(O,TP)
0 1 1... n nd d d d
.
3.2
(Threshold)
.
i
x,i di
[0,].
x=(x1,,xm).
x.
3.2.1
m-
.
1 i m , Si i
,
Si = ST,i
0,1,...n .
-
34
t=0, -.
1( ,..., )mY Y Y
1 1( ) ,..., , 0,1m
m mp y P Y y Y y y
.
( 1), 1,...,i iP P Y i m .
:
2 2
( , )( , )
( )( )
i j i ji j
i i j j
E y Y P Pp y Y
P P P P (3.4.1)
2 2 2 2
i i i i i i iY E Y P E Y P P P .
1
m
ii
M Y .
:
1
m
i i ii
L eY
ei i 0i 1
.
S Y.
S
Y, .
S :
1 (1) ( )( , , ) ( , , )d
m mS S S S
-
35
(1) ( )( ,..., )m (1,..., )m .
1,..., 1m m
-
S .
:
( 1), 1,...,iP Y i m : .
( 1,..., 1)i iP Y Y , 1, , 1,..., ,2i i m m
-.
:
2 1i i iE Y E Y P Y
21, 1i j i jE YY P Y Y
2
2,i jY Y
22
2, ,y i jP P Y Y i j
3.2.2
3.2.2: 1( ,..., )mX X X m-
mxnD dij i ,
i 1
...ni i
d d .
1i
d ( 1)ni
d
( 1)j ji i i iS j d X d , 0,..., , 1,...,j n i m
-
36
(X,D) 1( ,..., )mS S S .
x
( ) ( )i iF x P x x .
i- D - i.
, ( Si=0)
1i iX d i :
1( )i i ip F d .
( , )i jP Y Y i j
( Xi Xj).
( , )i jP Y Y (1)
1 1
( ) ( , )i j i i j jE YY P X d X d .
, Xi Xj
.
.
, .
.
: d-
[0,1]d .
-
37
1( ) ( , , )dC u C u u
.
C : [0,1] [0,1]dC
:
1) 1( , , )dC u u iu
2) (1,1,...,1, ,1, ,1)i iC u u 1,..., , [0,1]ii d u
3) 1 1( , , ),( , , ) [0,1]d
d db b i ib :
1
1
2...
1
1 1
... ( 1) ( ,..., ) 0dd
d
i ii di
i i
C u u
1j j
u 2j j
u b 1,...,j d .
(Sklar 1959). F 1, , dF F .
: [0,1] [0,1]dC , 1, , dX X
,
1 1 1( , , ) ( ),..., ( )d d dF X X C F X F X (4.3)
, ,
1 1 1...x x dRanF RanF RanF ( )i iRanF F R
1F . , C 1, , dF F
, F (i)
1, , dF F .
: 1( , , )dC u u Frchet:
1
1
max 1 ,0 ( ) min , ,d
i di
U d C u u u
-
38
: F 1, , dF F :
1
1
max ( ) 1 ,0 ( ) min ( ), , ( )d
i i di
F x d F x F x F x
F .
S .
3.2.2: ( , )X D ( , )X D
1( ,..., )mS S S 1( ,..., )mS S S .
:
i. S S .
( ) ( )i iP S j P S j , 0,..., , 1,...,j n i m
ii. X X C
.
-
1, , 1,...,i i m 1,...,i ip p . :
1 1 1 1 11 1 ,...,1,..., 1 ,..., ( ,..., )i i i i i i i i i ip Y Y P X d X d C P P ,
1,...,i i
C - C .
. X
Y . :
1,..., ,..., ,2C m
.
-
39
3.3 - -
()
.
3.3( Bernoulli): p m p-
1( ,..., ) ,
1( ,..., )mY Y Y Bernoulli ,
: 0,1iP , 1 i m , ,
Bernoulli
:
1( ) ( )i iP Y P
y y y1( ,..., )m 0,1m
:
y1
1( ) ( ) (1 ( ))i i
my y
i iiP Y P P
3.4 ( Poisson): p
, 1( ,..., )mY Y Y Poisson
, : 0,i , 1 i m
Y Poisson
i .
1
m
ii
M Y , Poisson i ,
M .
!
1
1
( )
( ) exp ( )
m
imi
ii
P M
-
40
3.3.1 Bernoulli
..
( ) : 0,1iP
, ,
Bernoulli
1( ) ( )i iP Y P
:
. Bernoulli
iP .
Bernoulli .
1( )Q p
P)S( .
Q q , m
Bernoulli q
q m.
(1 )mm
P M Q q q q
:
(1 ) q)mm
P M q q dS(
.
Bernoulli
.
-
41
iX ,
( )ip
( ) ( )i ip h x
: (0,1)h
( ) ( )h x x 1
( ) 1 exp( )h x x , =(1,,)
, .
3.3.2 Poisson
Credit Risk Poisson.
i Poisson i
:
i i ik w
0ik , 1,...,
pi i iW W W 1ij
j
W
p ( , )j jS 1,...,
2j j j 0j .
1jE
2
j j ( ) ( )i i i iE k E W k .
:
( 1) ( 0) ( 0 )i i iP Y P Y E P Y
iY Poisson :
( 0 ) (1 exp( )) ( )i i i i i iE P Y E kw k E W k
Poisson, 1
m
ii
M Y
Poisson
-
42
1
( )m
i ii
M Poi k w
M Poisson
, , S
( , ( 1))bN N .
p, M p
, :
1 1 1 1 1
( )p pm m m
i i i ij j j i iji i j j i
k w k w k w
,...,i pM M
jM
Poisson 1
( )m
i ij ji
k w , j j .
1,..., jM
,
:
1
pd
jj
M M
1
( )m
i ij ji
k w ,
jM .
3.3.3
Bernoulli.
.
.
-
43
i ie , i iY
i i
(0,1]
.
m :
( )
1
mm
ii
L L i i i iL e Y
:
(1) p- : 0,1pi
, , i iL
:
( )i iE L
(2) : p
( )
1
1 1lim lim ( )
mm
im mi
E Lm m
p .
.
(3) c 2
1
mi
i
ec
i m.
3.5.3: ( )
1
mm
ii
L L
1, 2, 3. ( )P
i iL
.
-
44
( )1lim mm
Lm
3.3.3: ( )
1
mm
ii
L L
1, 2, 3 S .
S q , . , 0q S .
:
( )1lim ( ) ( )mm
q L qm
.
Bernoulli,
.
3.3.4
Bernoulli. :
i. Bernoulli Monte Carlo.
ii. .
iii. Bernoulli
.
Bernoulli .
3.3.4 : p-
p m p-
-
45
1( ,..., ) , , 1, , mX X
.
3.3.4: (, ) m-
. p- ,
1i i
i x dY I Bernoulli
, :
1( ) ( )i i ip P X d
-
46
3.4 Monte Carlo
3.4.1
X , , ,F P ,
f.
( ) ( ) ( )e h x h x f x dx (3.4.1)
h.
( ) x Ah x I A .
(3.4.1)
X , Monte Carlo.
f.
3.1: (Monte Carlo intergration)
(1) 1, , nX X f.
(2) Monte Carlo 1
1( )
MC n
n ii
h Xn
Monte Carlo
( ).
g
r(x) :
( ), ( ) 0
( ) ( )
0, ( ) 0
f x g x
x g x
g x
r
:
-
47
( ) ( ) ( ) ( ( ) ( ))gh x r x g x dx E h X r X
:
3.2: ( )
(1) 1, , nX X g.
(2) IS : 1
1( ) ( )
IS n
n i ii
h X r Xn
.
IS Monte Carlo.
:
2 2 21var ( ) ( )IS
ng gE h x r xn
2 21var ( )MC
ng gE h xn
2 2( ) ( )gE h x r x
2( )gE h x .
,
IS
n
g.
- h .
( ) ( )( )
( ( ))
f x h xg x
E h x (3.4.2)
( ( ))
( )( )
E h xr x
h x
1 1 1( ) ( ) ( ( ))IS
h x r x E h x .
IS (3.4.2)
( ( ))E h x .
(3.4.2) IS .
-
48
IS
X .
t :
( ) ( ) ( )txxM t E e f x dx
x, .
( )xM t , IS :
( ) ( ) ( )txt xg x e f x M t
( )
( ) ( )( )
txt x
t
f xr x M t e
g x
t x.
( exp( ))( )
( )t t x
E x txEg x
M t
t , :
( ) : ( )tx
xx cE r x x c E I M t e (3.4.4) .
tx tce e x c 0t , :
( ) ( )tx tcx xx cE I M t e M t e
(3.4.3) t ,
t .
, t ln ( )xM t tc .
(3.4.3) :
( exp( ))ln ( )
( )x tx
d E x txM t tc c c
dt M t.
3.4.2 Bernoulli
)
0,1m
1Y .
-
49
:
1
1( ) (1 )i i
my y
i iiP Y P P , 0,1
my
iP .
L :
1 11
( ) (exp( )) ( ) ( 1 )i i im m m
teY teL i i i ii i
i
M t E t eY E e e P P
Q(t) : ;( )
tL
t p
t
eQ y E Y y
M t,
1 1
1
expexp( )
(1 )( ) exp( ) 1
i i
m
i i mi y yi i
t i iit i i
t eYteY
Q y P y P PM t te P P
,exp( )
exp( ) 1i i
t i
i i
te Pq y
te P P.
1
, ,1
(1 )i im
y yt t i ti ii
Q y q q , tilting
,t iq .
,t iq 1 t , t .
)
:
( ) ( )P L c .
.
:
3.3: (IS )
(1) ip
-
50
1
exp( ) ( )
exp( ) ( ) 1 ( )
mi i
ii i i i
te Pe c
te P P
( , )t t c tilting.
(2) n1 1,..., mY Y .
,
i-:
( , )
( , )
exp( ) ( )
exp( ) ( ) 1 ( )
c i i
c i i i
t e P
t e P P
(3) 1
( , ) exp( ) ( ) 1 ( )m
L i i iiM t te P P
L.
n1 1
m
i ii
L eY 1( )(1), , nL L .
IS :
1
,1
( , ) ( , )11
1( ) ( , ) exp
j
IS nj
n L c cL cj
M t I t Ln
) IS
Bernoulli
Gauss ( )ip (0, )pN .
( , )pN
p .
,
.
( )r :
1
1 1
1
1exp ( )
12( ) exp
1 2exp ( ) ( )
2
r
-
51
IS
3.4: ( IS Gauss)
(1) 1, , ( , )n pN I
(2) i 1
,1
( )IS
n i 1.
(3) IS :
1
,1
1
1( )
IS ISn
n ni ii
rn
: .
1
,1IS
n P L C , IS
P L C
IS g
11( ) ( )exp2
g P L c
.
,
P L C .
g IS .
,
:
11max exp2
P L c
-
52
3.4.3 Bernoulli
1,...,t n , tm
t tM
.
Qt (0,1), tM
. ,t t q tM Q B m q .
1 2, .
)
1 t n ,1 ,,..., tt t mY Y tm .
1
1
, ,( ,.., ) (1,..., )
,...,t
tt i t i
i i m
MY Y
t .
t tM mE
t tM mE
,
n-.
1 1
( 1)...( 1)1 1( 1)...( 1)
t
n nt t t
t tt t t t
M
M M M
mn n m m m
=1 :
-
53
1
1n
t
t t
M
n m
:
2
2
2
)
Qt .
, .
tm t , tM -
:
1 1 1
0
,1( ) (1 )
( , ) ( , )m b
b mm mP M q q dq
b b
:
1
,( , , )
( , )
nt t tt
t t
M b m MmL b data
M b
-
54
4 :
- .
,
, .
4.1
.
Frchet.
Frchet.
1( ,..., )dL L L ,
,
: d .
( )L .
( )L .
.
((L)),
( )L
L .
4.1: iF , 1,..,iL i n
.
, :
min ((L)) max
maxp .
(4.1) (4.1)
.
-
55
inf : , 1,...,
sup : , 1,...,
i i
i i
p L L F i d
p L L F i d
(4.2)
1,..., dF F (~)
.
4.1 1 VR
= VR.
VR(((L))
iF , 1,..,iL i d .
iL , .
4.1.1 (comonotonicity). 1,..., dX X
comotonic Frchet
1 1( , , ) min , ,d dM u u u u .
4.1.1: 0 1 1,..., dL L comotonic
.
1 1... ( ) ... ( )d dV R L L V R L V R L .
F L.
Fi,
C : F=C(F1,,Fd)
1,..., dL L C.
W C M
W M Frchet .
:
-
56
(2) oC C oC
1,...,d
dX X X 1 1 1,..., , ,i i i dX X X X X .
1d
dX ( ) sup : ,x d d d ds x X x s
s .
c d , s :
, 1 ( )( , , )c d s cF F L S
1 1
, 1 ( ) 1 1 1 1,...,
( , , ) sup ( ), , ( ), ( )d
d
c d s d d d xx x
F F C F x F x F s
( )dF x dF x .
:
( ) inf : , 1,...,i im s P L s L F i d
, 1 ( )( , , ) :c d s dF F c C
dC - .
4.1.1 ( )
L 1( 2)d d 1,..., dF F copula C.
oC oC C .
: d , s
, 1 ( ) , 1 ( )( , , ) ( , , )c d s c d sF F F F (4.1.1)
, :
-
57
1
max , ( ) , ,1( )
min ,...,
d
ot
d
t C u u tC u
u u
, 1 ( )( ,..., )oC d st F F (4.4.1)
, 1,max ( ,..., )oC dV R F F
. (4.4.1) :
,maxV R L V R
0 1 , (4.1).
(4.1.2) ( )
F 1 dF F F .
0S 1F F .
( 1)
0,( ) 1 ( )
s d r
rr s dm s d inF F x dx
-
58
4.2
4.2.1
d
1,..., dL L .
.
:
. (L), 1
d
ii
L L
.
.
. (L)
.
.
,
1,..., dL L (C1,,ACd).
(L) =1
d
ii
AC
.
1,..., dL L , , ,F P ,
d .
\ 0d .
, 1
( )d
i ii
L L .
M
( ) :L .
-
59
: ( ) ( )Lk k
( )k
.
4.2: k \ 0d ,
1 . :r d
, :
( )
1
( ) ( )d
ri i
i
k
k (4.2)
( )r
i
iL , ( )L .
i iL ( )r
i i
(4.2) ( )
.
4.2.2 Euler
,
.
, :
( ) ( )t tk k , 0,t
( ) : k
.
Euler, k
, :
1
( ) ( )d
iii
rkk (4.2.2)
(4.2) (4.2.2) .
-
60
4.2.2: ( Euler)
,
, Euler :
:r dk , ( ) ( )
r
i
rk k
(4.2.3)
Euler :
( ) ( )r
rk k .
4.2.2 ( )
( ) ( ( ))SDr v r L
1,..., dL L .
12( )SDr
1
cov( , )cov( , ( ))
( ) ( )( ) var( )
SD
d
i j jr jSD i
iSD
L Lr L L
r L
=1, i-
:
cov( , )(1) , (1)
var( )
SDr ii i
L LAC L L
L
4.2.2 : :
,
. (0, , )dL E ( ). ,
Euler, :
-
61
1
1
(1)
(1)
d
ri
i ir d
jj
j
AC
AC
k
k , 1 i j d (4.1.9) (4.2.4)
4.2.3 Euler
4.2.3: k , ,
r .
r
, , :
0,( )( ) ( )
( )0,
( )( )
i i
r
i i i
r
E L E L
rE L
r E L E L
r
k
k
k
k
k
i
r
i ,
i i
.
4.2.3 : 4.2.3
Euler.
.
1
( ) ( )d
ii
L Lk k ,
.
,
( )i iAC Lk .
-
62
4.2.4: ,
, r
,
0,1d
, .
1 1
1
( ) ( ,..., )d
ri i d di
i
rk k (4.2.5)
(4.1.3),
(4.2.5) =1.
,
, 1
( )d
i ii
L L .
:
1 c
d
i i i i i ii i i
L L L
k k k
.
-
63
5 :
,
.
.
5.1 NSF
5.1: ( )
N(t) 0,t
1 2, ,X X . :
( )
( )
1
N t
N tS X (5.1)
( )( ) ( )NS N tF x P S x
.
, NS NSF .
NS
F
( )x .
5.1 (, )
x
, (0) 0 . ( )x
, (5.1)
. ( ) ( )Np P N ,
0,1,2,... . .
-
64
5.1 ( ) : NS ,
5.1, 0x :
( )
0
( ) ( ) ( ) ( )NS N
F x P S x x (5.2)
( )( ) ( )Kx P S x - .
(0)( ) 1x
0x (0)( ) 0x 0x .
(5.2) ,
.
.
:
0
( ) ( )sxF s e dF x , 0s
Laplace-Stieltjes, ( )( ) ( )s s .
:
0
( ) ( ) ( ) , 0 NS N N
F s P s M s s
.
5.2 ( )
(5.1) ( ) 2,NE
1( ) ( ) ( )NE S E N E x 2
1 1( ) ( ) ( ) ( )Nv r S v r N E x E N v r x
-
65
5.2 Poisson
Poisson
.
Poisson
.
0,1
.
, nk 1 np
1,
n n 1,...,n .
.
n
n pn:
( ) (1 ) , 0,...,nn n nn
P N p p n
( )
0
( ) ( ) ( )NS N N
F x P S x p x
.
n lim 0nn
np ,
lim ( ) , 0,1,2,...nn
P N e
-
66
5.2 ( Poisson)
( , ), 1,...,iN i i
S CPoi i d
, 1
( , )i
d
N Ni
S S CPoi ,
1
d
ii
1
di
ii
5.3
.
NS
F
, .
.
Poisson ( , )nS CPoi .
NS
F
NS
F .
: iX (
) NS iX . :
1
2
1 1
( ) ( ) ( )( )
( )( ) ( ) ( ) ( )
N
N NS
N
S E S x E N E XF x
v r Sv r N E X E N v r X
: NS k Y ,
k ( , )Y . (k, , )
, k Y
NS , :
-
67
1( )k E X 212
( )E X
31
321
( )2
( )
E X
E X
.
.
Figure 10.4: Simulated CPoi(100,Exp(1)) data together with normal- and translated- gamma
approximations (log-log scale). The 99.9% quantile estimates are also given.
10.4 120x .
90% NS
F .
.
.
5.4 Paujer
.
-
68
1x
1 0( ) 1P x 1( )g P x , ( )P P N .
0 0g ( )
1( ... )n
ig P x x ,
g .
1( 1) ( )
1
n ni
i
g g g .
:
0 0( 0) ( 0)NS P S P N P (5.3)
( )
1
( ) , 1n N nS P S n p g n
(5.7) ( )ng .
(5.3)
.
(5.4) ( Paujer): (p)
Paujer (, b) ,b , :
1r r
bp P
r 1r .
: ( , )N B n P
(1 )r n rrn
p p pr
0 r n
1
( 1)
1 (1 )r
r
P p n P
P p r p
Paujer (,b) 1
p
p
( 1)
(1 )
n Pb
p
-
69
5.4 ( Paujer)
Paujer(,b) 0 1( 0) 0g P x ,
0 0S P 1, 11
ri
r i ri
bS g S .
5.5 Poisson
Poisson ( , )CPoi ( )N Poi
F . Poisson
( ) ( )v r N E N ,
( ) ( )v r N E N
.
( )F .
0 0( ) ( ) ( ) ( ) ( )NP P N P N dF e dF
5.5 ( Poisson).
0
( ) ( )NP e dF
Poisson F .
5.5: Poisson
F . ( ) ( )E N E ( ) ( ) ( )v r N E v r .
-
70
5.6 ( Poisson)
Poisson
( , ) .
( , )1
N NB
5.6 Poisson
[0,1].
, (t)
[0,t] 0t .
(t), 0t
.
5.6 ( ). 0
( )t
N N t
, 0 1 20, , ,...T T T
1
( )kT t
N t I .
5.7 ( Poisson).
0
( )t
N N t Poisson
>0 :
i)
ii) (0)=0 ,
iii)
iv) 0t , ( ) ( )N t Poi t
5.6: iii) iv) 0 u t
()-(u) (t)-() 0 :
-
71
( )( )
( ) ( ) ( ) uu
P N N u P N u e
()-(u)
(u,] (-u).
5.6 ( Poisson).
.
.
(1) Poisson >0
(2)
( ) 1 0( )P N t t t , 0t
( ) 2 0( )P N t t , 0t
(3) 1 1
( )Exp .
(4) 0t , ( ) ( )N t Poi t ( )N t ,
1 2, ,...,T T T
.
1 1, , / ( ) 1 0 ...
( , , )T T N t t t tf t t It
-
72
5.7 Poisson
Poisson ,
.
5.7 (- Poisson). -
Poisson , ( ) 0s , :
i) (0) 0N
ii) N
iii) 0t ( ) ( ) 1 ( ) 0( )P N t h N t t h h , 0h
( ) ( ) 2 0( )P N t h N t h , 0h
5.7 ( , ). -
Poisson 0t
1( ) ( )N t N t , N Poisson.
N , .
-
73
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Default risk insurance and incomplete market ,Mathematical Finance
,Artzner C. ,Delbaen F.,(1995)
On the coherence of expected shortfall,Journal of Banking and
Finance, Acerbi C.,Tasche D.(2002)
Statistical Models Based on Counting Processes,Andersen P.,Gill
R.,Keiding N.,Springer(1993)
Market Models ,A Guide to Financial Data Analysis,Alexander
C.,Wiley,(2001)