  


 1952 .     ,  
          -
.     ,     -
       .   
    ,   
 (holding period).        ,
     ,      -
  ,        ( -
     ).  ,     -
   ,      t = 0, 
   t = 1.   t = 0    
    ,        -
 t = .        ,
         -
.        
.

    t = 0,     ,  
  (,  ,  )    -
 .      ( ) 
(expected returns)   ,    ,
         . (-
       . 18.)  ,
      ,       -
,    ,   ,  
   ,   .  ,  -
,       -
  (..  (risk)),     
,          
 t = 0.        
   .

       -
      ,    . -
         -
      .