<PAGE>   1

                                                                    EXHIBIT 11.1


                           HMT TECHNOLOGY CORPORATION

           STATEMENT REGARDING COMPUTATION OF NET INCOME PER SHARE (1)
                      (In thousands, except per share data)


<TABLE>
<CAPTION>
                                                          QUARTER ENDED        SIX MONTHS ENDED
                                                           SEPTEMBER 30,          SEPTEMBER 30,
                                                       1998         1997      1998         1997
                                                       ----         ----      ----         ----
                                                          (Unaudited)            (Unaudited)
<S>                                                   <C>         <C>         <C>           <C>
      Basic:
      Weighted average shares outstanding
         for the period......................         43,570       41,832     43,461      41,484
                                                      ------      -------     ------     -------
      Shares used in computing per share
         amounts.............................         43,570       41,832     43,461      41,484
                                                      ======      =======     ======     =======
      Net income available for common
         stockholders........................           $505      $19,064     $1,597     $34,433
                                                      ======      =======     ======     =======
      Net income available for common
         stockholders per share..............          $0.01        $0.46      $0.04       $0.83
                                                      ======      =======     ======     =======
      Diluted:
      Weighted average shares outstanding
         for the period......................         43,570       41,832     43,461      41,484
      Net effect of dilutive stock options-
         based on the treasury stock method
         using average market price..........          1,680        2,965      1,804       2,977
      Assumed conversion of 53/4%
         convertible subordinated notes......             --        9,684         --          --
                                                      ------      -------     ------     -------
      Shares used in computing per share
         amounts.............................         45,249       54,482     45,264      54,145
                                                      ======      =======     ======     =======
      Net income available for common                                        
         stockholders........................           $505      $19,064     $1,597     $34,433
                                                      ======      =======     ======     =======
     Add 5 3/4% convertible subordinated                                                 
         note interest, net of interest                                         
         capitalized and income tax effect...             --        1,541         --       2,876
                                                      ------      -------     ------     -------
     Net income available for common                  
         stockholders........................           $505      $20,705     $1,597     $37,309
                                                      ======      =======     ======     =======
     Net income available for common           
         stockholders per share..............          $0.01        $0.38      $0.04       $0.69
                                                      ======      =======     ======     =======
</TABLE>

(2)  Diluted EPS for the three and six months ended September 30, 1998 does not
assume conversion of the Company's 5 3/4% convertible subordinated notes, as the
effect would be anti-dilutive.


                                       15