proc expand内的movmax计算不同股票的5日后中最高价问题

想计算各支股票每日的后面5天、60天、250天内的最大涨幅，假设当日股价nclose,Fmax5即为nclose和后面4天股价的5各数值最大值。想着如果把每支股票日期都倒过来，就能用proc expand的movmax函数；但是遇到问题时该函数把所有股票一起生成TIME排了序，导致不同股票交界时计算错用了其它股票数据。求大神协助如何即可以用proc expand的movmax函数,又能避免不同股票交界的数据混用计算问题。或者数组循环解决
data stock.test3;
  set stock.test;
   proc sort data=stock.test3;
by stockcode descending date;      
run;


proc expand data=stock.test3 Out=Stock.test3 method=none;
   convert nclose = Fmax5 / transformout = (movmax 5);
   convert nclose = Fmin5 / transformout = (movmin 5);

proc sort data=stock.test3 out=stock.test3;
by stockcode date;

run;

proc sort data=stock.test out=test;
  by stockcode descending date;
run;

proc expand data=test Out=testout method=none;
        by stockcode;
        convert nclose = max5_close / transformout = (movmax 5);
        convert nclose = max60_close / transformout = (movmax 60);
        convert nclose = max250_close / transformout = (movmax 250);
run;

proc sort data=testout out=testfinal;
  by stockcode date;
run;