是不是这样
proc transpose data=liao prefix=r out=liao_1 (drop = _name_);;
     by stock year;
         var r;
         id month;
run;

data liao_2;
    set liao_1;
        ret=(r5+1)*(r6+1)*(r7+1)*(r8+1)*(r9+1)*(r10+1)*(r11+1)*(r12+1)*(r1+1)*(r2+1)*(r3+1)*(r4+1)-1;
        drop r1-r12;
run;

proc sort data=have;
by stock year month;
run;

data want;
set have;
by stock year;
retain ret_yr;
if first.year then ret_yr=1+r;
else ret_yr=ret_yr*(1+r);
run;

data want(drop=r);
set want;
by stock year;
if last.year then ret_yr=ret_yr-1;
else delete;
run;

很好

你好 股票月收益率怎么计算呢