HMT TECHNOLOGY CORP
SC 13G/A, 1999-02-12
COMPUTER STORAGE DEVICES
Previous: HMT TECHNOLOGY CORP, POS AM, 1999-02-12
Next: HMT TECHNOLOGY CORP, SC 13G, 1999-02-12



<PAGE>   1
                                                      ------------------------
                                                              OMB APPROVAL
                                                      ------------------------
                                                      OMB Number: 3235-0145
                                                      Expires: August 31, 1999
                                                      Estimated average burden
                                                      hours per response..14.90

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549



                                  SCHEDULE 13G



                    UNDER THE SECURITIES EXCHANGE ACT OF 1934

                               (AMENDMENT NO. 2 )*


                           HMT Technology Corporation
                                (Name of Issuer)


                          Common Stock, $.001 par value
                         (Title of Class of Securities)


                                    403917107
                                 (CUSIP Number)


                                December 31, 1998
             (Date of Event Which Requires Filing of this Statement)


         Check the appropriate box to designate the rule pursuant to which this
         Schedule is filed:


              / /  Rule 13d-1(b)
              / /  Rule 13d-1(c)
              /x/  Rule 13d-1(d)


         *The remainder of this cover page shall be filled out for a reporting
         person's initial filing on this form with respect to the subject class
         of securities, and for any subsequent amendment containing information
         which would alter the disclosures provided in a prior cover page.

         The information required in the remainder of this cover page shall not
         be deemed to be "filed" for the purpose of Section 18 of the Securities
         Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of
         that section of the Act but shall be subject to all other provisions of
         the Act (however, see the Notes).


                               Page 1 of 39 Pages
<PAGE>   2
- -------------------------                          -----------------------------
CUSIP NO.  0004039171                    13G       PAGE    2   OF  39  PAGES
- -------------------------                          -----------------------------



- --------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

                 Summit Ventures III, L.P.

- --------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                            (a) / /
                                                            (b) / /

- --------------------------------------------------------------------------------
  3     SEC USE ONLY


- --------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

                 Delaware limited partnership

- --------------------------------------------------------------------------------
                     5    SOLE VOTING POWER

                                   0 shares

                     -----------------------------------------------------------
     NUMBER OF       6    SHARED VOTING POWER
      SHARES    
   BENEFICIALLY                    2,733,940 shares
     OWNED BY   
       EACH          -----------------------------------------------------------
    REPORTING        7    SOLE DISPOSITIVE POWER
      PERSON 
       WITH                        0 shares

                     -----------------------------------------------------------
                     8    SHARED DISPOSITIVE POWER

                                   2,733,940 shares

- --------------------------------------------------------------------------------
  9    AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                 2,733,940 shares

- --------------------------------------------------------------------------------
  10   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
                                                                             / /

- --------------------------------------------------------------------------------
  11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                 6.26%

- --------------------------------------------------------------------------------
  12   TYPE OF REPORTING PERSON *

                 PN

- --------------------------------------------------------------------------------
                      *SEE INSTRUCTIONS BEFORE FILLING OUT!


                               Page 2 of 39 Pages
<PAGE>   3
- -------------------------                          -----------------------------
CUSIP NO.  0004039171                    13G       PAGE    3   OF  39  PAGES
- -------------------------                          -----------------------------



- --------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

                 Summit Partners III, L.P.

- --------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                            (a) / /
                                                            (b) / /

- --------------------------------------------------------------------------------
  3     SEC USE ONLY


- --------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

                 Delaware limited partnership

- --------------------------------------------------------------------------------
                     5    SOLE VOTING POWER

                                   0 shares

                     -----------------------------------------------------------
     NUMBER OF       6    SHARED VOTING POWER
      SHARES    
   BENEFICIALLY                    2,733,940 shares
     OWNED BY   
       EACH          -----------------------------------------------------------
    REPORTING        7    SOLE DISPOSITIVE POWER
      PERSON 
       WITH                        0 shares

                     -----------------------------------------------------------
                     8    SHARED DISPOSITIVE POWER

                                   2,733,940 shares

- --------------------------------------------------------------------------------
  9    AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                 2,733,940 shares

- --------------------------------------------------------------------------------
  10   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
                                                                             / /

- --------------------------------------------------------------------------------
  11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                 6.26%

- --------------------------------------------------------------------------------
  12   TYPE OF REPORTING PERSON *

                 PN

- --------------------------------------------------------------------------------
                      *SEE INSTRUCTIONS BEFORE FILLING OUT!



                               Page 3 of 39 Pages
<PAGE>   4
- -------------------------                          -----------------------------
CUSIP NO.  0004039171                    13G       PAGE    4   OF  39  PAGES
- -------------------------                          -----------------------------



- --------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

                 Summit Subordinated Debt Fund, L.P.

- --------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                            (a) / /
                                                            (b) / /

- --------------------------------------------------------------------------------
  3     SEC USE ONLY


- --------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

                 Delaware limited partnership

- --------------------------------------------------------------------------------
                     5    SOLE VOTING POWER

                                   0 shares

                     -----------------------------------------------------------
     NUMBER OF       6    SHARED VOTING POWER
      SHARES    
   BENEFICIALLY                    2,733,940 shares
     OWNED BY   
       EACH          -----------------------------------------------------------
    REPORTING        7    SOLE DISPOSITIVE POWER
      PERSON 
       WITH                        0 shares

                     -----------------------------------------------------------
                     8    SHARED DISPOSITIVE POWER

                                   2,733,940 shares

- --------------------------------------------------------------------------------
  9    AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                 2,733,940 shares

- --------------------------------------------------------------------------------
  10   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
                                                                             / /

- --------------------------------------------------------------------------------
  11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                 6.26%

- --------------------------------------------------------------------------------
  12   TYPE OF REPORTING PERSON *

                 PN

- --------------------------------------------------------------------------------
                      *SEE INSTRUCTIONS BEFORE FILLING OUT!



                               Page 4 of 39 Pages
<PAGE>   5
- -------------------------                          -----------------------------
CUSIP NO.  0004039171                    13G       PAGE    5   OF  39  PAGES
- -------------------------                          -----------------------------



- --------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

                 Summit Ventures IV, L.P.

- --------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                            (a) / /
                                                            (b) / /

- --------------------------------------------------------------------------------
  3     SEC USE ONLY


- --------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

                 Delaware limited partnership

- --------------------------------------------------------------------------------
                     5    SOLE VOTING POWER

                                   0 shares

                     -----------------------------------------------------------
     NUMBER OF       6    SHARED VOTING POWER
      SHARES    
   BENEFICIALLY                    2,733,940 shares
     OWNED BY   
       EACH          -----------------------------------------------------------
    REPORTING        7    SOLE DISPOSITIVE POWER
      PERSON 
       WITH                        0 shares

                     -----------------------------------------------------------
                     8    SHARED DISPOSITIVE POWER

                                   2,733,940 shares

- --------------------------------------------------------------------------------
  9    AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                 2,733,940 shares

- --------------------------------------------------------------------------------
  10   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
                                                                             / /

- --------------------------------------------------------------------------------
  11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                 6.26%

- --------------------------------------------------------------------------------
  12   TYPE OF REPORTING PERSON *

                 PN

- --------------------------------------------------------------------------------
                      *SEE INSTRUCTIONS BEFORE FILLING OUT!



                               Page 5 of 39 Pages
<PAGE>   6
- -------------------------                          -----------------------------
CUSIP NO.  0004039171                    13G       PAGE    6   OF  39  PAGES
- -------------------------                          -----------------------------



- --------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

                 Summit Partners IV, L.P.

- --------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                            (a) / /
                                                            (b) / /

- --------------------------------------------------------------------------------
  3     SEC USE ONLY


- --------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

                 Delaware limited partnership

- --------------------------------------------------------------------------------
                     5    SOLE VOTING POWER

                                   0 shares

                     -----------------------------------------------------------
     NUMBER OF       6    SHARED VOTING POWER
      SHARES    
   BENEFICIALLY                    2,733,940 shares
     OWNED BY   
       EACH          -----------------------------------------------------------
    REPORTING        7    SOLE DISPOSITIVE POWER
      PERSON 
       WITH                        0 shares

                     -----------------------------------------------------------
                     8    SHARED DISPOSITIVE POWER

                                   2,733,940 shares

- --------------------------------------------------------------------------------
  9    AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                 2,733,940 shares

- --------------------------------------------------------------------------------
  10   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
                                                                             / /

- --------------------------------------------------------------------------------
  11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                 6.26%

- --------------------------------------------------------------------------------
  12   TYPE OF REPORTING PERSON *

                 PN

- --------------------------------------------------------------------------------
                      *SEE INSTRUCTIONS BEFORE FILLING OUT!



                               Page 6 of 39 Pages
<PAGE>   7
- -------------------------                          -----------------------------
CUSIP NO.  0004039171                    13G       PAGE    7   OF  39  PAGES
- -------------------------                          -----------------------------



- --------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

                 Summit Partners SD, L.P.

- --------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                            (a) / /
                                                            (b) / /

- --------------------------------------------------------------------------------
  3     SEC USE ONLY


- --------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

                 Delaware limited partnership

- --------------------------------------------------------------------------------
                     5    SOLE VOTING POWER

                                   0 shares

                     -----------------------------------------------------------
     NUMBER OF       6    SHARED VOTING POWER
      SHARES    
   BENEFICIALLY                    2,733,940 shares
     OWNED BY   
       EACH          -----------------------------------------------------------
    REPORTING        7    SOLE DISPOSITIVE POWER
      PERSON 
       WITH                        0 shares

                     -----------------------------------------------------------
                     8    SHARED DISPOSITIVE POWER

                                   2,733,940 shares

- --------------------------------------------------------------------------------
  9    AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                 2,733,940 shares

- --------------------------------------------------------------------------------
  10   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
                                                                             / /

- --------------------------------------------------------------------------------
  11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                 6.26%

- --------------------------------------------------------------------------------
  12   TYPE OF REPORTING PERSON *

                 PN

- --------------------------------------------------------------------------------
                      *SEE INSTRUCTIONS BEFORE FILLING OUT!



                               Page 7 of 39 Pages
<PAGE>   8
- -------------------------                          -----------------------------
CUSIP NO.  0004039171                    13G       PAGE    8   OF  39  PAGES
- -------------------------                          -----------------------------



- --------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

                 Summit Investors II, L.P.

- --------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                            (a) / /
                                                            (b) / /

- --------------------------------------------------------------------------------
  3     SEC USE ONLY


- --------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

                 Delaware limited partnership

- --------------------------------------------------------------------------------
                     5    SOLE VOTING POWER

                                   0 shares

                     -----------------------------------------------------------
     NUMBER OF       6    SHARED VOTING POWER
      SHARES    
   BENEFICIALLY                    2,733,940 shares
     OWNED BY   
       EACH          -----------------------------------------------------------
    REPORTING        7    SOLE DISPOSITIVE POWER
      PERSON 
       WITH                        0 shares

                     -----------------------------------------------------------
                     8    SHARED DISPOSITIVE POWER

                                   2,733,940 shares

- --------------------------------------------------------------------------------
  9    AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                 2,733,940 shares

- --------------------------------------------------------------------------------
  10   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
                                                                             / /

- --------------------------------------------------------------------------------
  11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                 6.26%

- --------------------------------------------------------------------------------
  12   TYPE OF REPORTING PERSON *

                 PN

- --------------------------------------------------------------------------------
                      *SEE INSTRUCTIONS BEFORE FILLING OUT!



                               Page 8 of 39 Pages
<PAGE>   9
- -------------------------                          -----------------------------
CUSIP NO.  0004039171                    13G       PAGE    9   OF  39  PAGES
- -------------------------                          -----------------------------



- --------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

                 Stamps, Woodsum & Co. III

- --------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                            (a) / /
                                                            (b) / /

- --------------------------------------------------------------------------------
  3     SEC USE ONLY


- --------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

                 Massachusetts general partnership

- --------------------------------------------------------------------------------
                     5    SOLE VOTING POWER

                                   0 shares

                     -----------------------------------------------------------
     NUMBER OF       6    SHARED VOTING POWER
      SHARES    
   BENEFICIALLY                    2,733,940 shares
     OWNED BY   
       EACH          -----------------------------------------------------------
    REPORTING        7    SOLE DISPOSITIVE POWER
      PERSON 
       WITH                        0 shares

                     -----------------------------------------------------------
                     8    SHARED DISPOSITIVE POWER

                                   2,733,940 shares

- --------------------------------------------------------------------------------
  9    AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                 2,733,940 shares

- --------------------------------------------------------------------------------
  10   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
                                                                             / /

- --------------------------------------------------------------------------------
  11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                 6.26%

- --------------------------------------------------------------------------------
  12   TYPE OF REPORTING PERSON *

                 PN

- --------------------------------------------------------------------------------
                      *SEE INSTRUCTIONS BEFORE FILLING OUT!



                               Page 9 of 39 Pages
<PAGE>   10
- -------------------------                          -----------------------------
CUSIP NO.  0004039171                    13G       PAGE    10  OF  39  PAGES
- -------------------------                          -----------------------------



- --------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

                 Stamps, Woodsum & Co. IV

- --------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                            (a) / /
                                                            (b) / /

- --------------------------------------------------------------------------------
  3     SEC USE ONLY


- --------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

                 Massachusetts general partnership

- --------------------------------------------------------------------------------
                     5    SOLE VOTING POWER

                                   0 shares

                     -----------------------------------------------------------
     NUMBER OF       6    SHARED VOTING POWER
      SHARES    
   BENEFICIALLY                    2,733,940 shares
     OWNED BY   
       EACH          -----------------------------------------------------------
    REPORTING        7    SOLE DISPOSITIVE POWER
      PERSON 
       WITH                        0 shares

                     -----------------------------------------------------------
                     8    SHARED DISPOSITIVE POWER

                                   2,733,940 shares

- --------------------------------------------------------------------------------
  9    AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                 2,733,940 shares

- --------------------------------------------------------------------------------
  10   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
                                                                             / /

- --------------------------------------------------------------------------------
  11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                 6.26%

- --------------------------------------------------------------------------------
  12   TYPE OF REPORTING PERSON *

                 PN

- --------------------------------------------------------------------------------
                      *SEE INSTRUCTIONS BEFORE FILLING OUT!



                              Page 10 of 39 Pages
<PAGE>   11
- -------------------------                          -----------------------------
CUSIP NO.  0004039171                    13G       PAGE    11  OF  39  PAGES
- -------------------------                          -----------------------------



- --------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

                 E. Roe Stamps, IV

- --------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                            (a) / /
                                                            (b) / /

- --------------------------------------------------------------------------------
  3     SEC USE ONLY


- --------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

                 United States

- --------------------------------------------------------------------------------
                     5    SOLE VOTING POWER

                                   0 shares

                     -----------------------------------------------------------
     NUMBER OF       6    SHARED VOTING POWER
      SHARES    
   BENEFICIALLY                    2,733,940 shares
     OWNED BY   
       EACH          -----------------------------------------------------------
    REPORTING        7    SOLE DISPOSITIVE POWER
      PERSON 
       WITH                        0 shares

                     -----------------------------------------------------------
                     8    SHARED DISPOSITIVE POWER

                                   2,733,940 shares

- --------------------------------------------------------------------------------
  9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                 2,733,940 shares

- --------------------------------------------------------------------------------
10      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
                                                                             / /

- --------------------------------------------------------------------------------
   11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                 6.26%

- --------------------------------------------------------------------------------
   12   TYPE OF REPORTING PERSON *

                 IN

- --------------------------------------------------------------------------------
                      *SEE INSTRUCTIONS BEFORE FILLING OUT!



                              Page 11 of 39 Pages
<PAGE>   12
- -------------------------                          -----------------------------
CUSIP NO.  0004039171                    13G       PAGE   12   OF  39  PAGES
- -------------------------                          -----------------------------



- --------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

                 Stephen G. Woodsum

- --------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                            (a) / /
                                                            (b) / /

- --------------------------------------------------------------------------------
  3     SEC USE ONLY


- --------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

                 United States

- --------------------------------------------------------------------------------
                     5    SOLE VOTING POWER

                                   0 shares

                     -----------------------------------------------------------
     NUMBER OF       6    SHARED VOTING POWER
      SHARES    
   BENEFICIALLY                    2,733,940 shares
     OWNED BY   
       EACH          -----------------------------------------------------------
    REPORTING        7    SOLE DISPOSITIVE POWER
      PERSON 
       WITH                        0 shares

                     -----------------------------------------------------------
                     8    SHARED DISPOSITIVE POWER

                                   2,733,940 shares

- --------------------------------------------------------------------------------
  9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                 2,733,940 shares

- --------------------------------------------------------------------------------
10      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
                                                                             / /

- --------------------------------------------------------------------------------
   11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                 6.26%

- --------------------------------------------------------------------------------
   12   TYPE OF REPORTING PERSON *

                 IN

- --------------------------------------------------------------------------------
                      *SEE INSTRUCTIONS BEFORE FILLING OUT!



                              Page 12 of 39 Pages
<PAGE>   13
- -------------------------                          -----------------------------
CUSIP NO.  0004039171                    13G       PAGE    13  OF  39  PAGES
- -------------------------                          -----------------------------



- --------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

                 Gregory M. Avis

- --------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                            (a) / /
                                                            (b) / /

- --------------------------------------------------------------------------------
  3     SEC USE ONLY


- --------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

                 United States

- --------------------------------------------------------------------------------
                     5    SOLE VOTING POWER

                                   0 shares

                     -----------------------------------------------------------
     NUMBER OF       6    SHARED VOTING POWER
      SHARES    
   BENEFICIALLY                    2,733,940 shares
     OWNED BY   
       EACH          -----------------------------------------------------------
    REPORTING        7    SOLE DISPOSITIVE POWER
      PERSON 
       WITH                        0 shares

                     -----------------------------------------------------------
                     8    SHARED DISPOSITIVE POWER

                                   2,733,940 shares

- --------------------------------------------------------------------------------
  9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                 2,733,940 shares

- --------------------------------------------------------------------------------
10      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
                                                                             / /

- --------------------------------------------------------------------------------
   11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                 6.26%

- --------------------------------------------------------------------------------
   12   TYPE OF REPORTING PERSON *

                 IN

- --------------------------------------------------------------------------------
                      *SEE INSTRUCTIONS BEFORE FILLING OUT!



                              Page 13 of 39 Pages
<PAGE>   14
- -------------------------                          -----------------------------
CUSIP NO.  0004039171                    13G       PAGE    14  OF  39  PAGES
- -------------------------                          -----------------------------



- --------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

                 John A. Genest

- --------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                            (a) / /
                                                            (b) / /

- --------------------------------------------------------------------------------
  3     SEC USE ONLY


- --------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

                 United States

- --------------------------------------------------------------------------------
                     5    SOLE VOTING POWER

                                   0 shares

                     -----------------------------------------------------------
     NUMBER OF       6    SHARED VOTING POWER
      SHARES    
   BENEFICIALLY                    2,733,940 shares
     OWNED BY   
       EACH          -----------------------------------------------------------
    REPORTING        7    SOLE DISPOSITIVE POWER
      PERSON 
       WITH                        0 shares

                     -----------------------------------------------------------
                     8    SHARED DISPOSITIVE POWER

                                   2,733,940 shares

- --------------------------------------------------------------------------------
  9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                 2,733,940 shares

- --------------------------------------------------------------------------------
10      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
                                                                             / /

- --------------------------------------------------------------------------------
   11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                 6.26%

- --------------------------------------------------------------------------------
   12   TYPE OF REPORTING PERSON *

                 IN

- --------------------------------------------------------------------------------
                      *SEE INSTRUCTIONS BEFORE FILLING OUT!



                              Page 14 of 39 Pages
<PAGE>   15
- -------------------------                          -----------------------------
CUSIP NO.  0004039171                    13G       PAGE    15   OF  39  PAGES
- -------------------------                          -----------------------------



- --------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

                 Martin J. Mannion

- --------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                            (a) / /
                                                            (b) / /

- --------------------------------------------------------------------------------
  3     SEC USE ONLY


- --------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

                 United States

- --------------------------------------------------------------------------------
                     5    SOLE VOTING POWER

                                   0 shares

                     -----------------------------------------------------------
     NUMBER OF       6    SHARED VOTING POWER
      SHARES    
   BENEFICIALLY                    2,733,940 shares
     OWNED BY   
       EACH          -----------------------------------------------------------
    REPORTING        7    SOLE DISPOSITIVE POWER
      PERSON 
       WITH                        0 shares

                     -----------------------------------------------------------
                     8    SHARED DISPOSITIVE POWER

                                   2,733,940 shares

- --------------------------------------------------------------------------------
  9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                 2,733,940 shares

- --------------------------------------------------------------------------------
10      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
                                                                             / /

- --------------------------------------------------------------------------------
   11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                 6.26%

- --------------------------------------------------------------------------------
   12   TYPE OF REPORTING PERSON *

                 IN

- --------------------------------------------------------------------------------
                      *SEE INSTRUCTIONS BEFORE FILLING OUT!



                              Page 15 of 39 Pages
<PAGE>   16
- -------------------------                          -----------------------------
CUSIP NO.  0004039171                    13G       PAGE    16  OF  39  PAGES
- -------------------------                          -----------------------------



- --------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

                 Bruce R. Evans

- --------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                            (a) / /
                                                            (b) / /

- --------------------------------------------------------------------------------
  3     SEC USE ONLY


- --------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

                 United States

- --------------------------------------------------------------------------------
                     5    SOLE VOTING POWER

                                   0 shares

                     -----------------------------------------------------------
     NUMBER OF       6    SHARED VOTING POWER
      SHARES    
   BENEFICIALLY                    2,733,940 shares
     OWNED BY   
       EACH          -----------------------------------------------------------
    REPORTING        7    SOLE DISPOSITIVE POWER
      PERSON 
       WITH                        0 shares

                     -----------------------------------------------------------
                     8    SHARED DISPOSITIVE POWER

                                   2,733,940 shares

- --------------------------------------------------------------------------------
  9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                 2,733,940 shares

- --------------------------------------------------------------------------------
10      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
                                                                             / /

- --------------------------------------------------------------------------------
   11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                 6.26%

- --------------------------------------------------------------------------------
   12   TYPE OF REPORTING PERSON *

                 IN

- --------------------------------------------------------------------------------
                      *SEE INSTRUCTIONS BEFORE FILLING OUT!



                              Page 16 of 39 Pages
<PAGE>   17
- -------------------------                          -----------------------------
CUSIP NO.  0004039171                    13G       PAGE   17   OF  39  PAGES
- -------------------------                          -----------------------------



- --------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

                 Thomas S. Roberts

- --------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                            (a) / /
                                                            (b) / /

- --------------------------------------------------------------------------------
  3     SEC USE ONLY


- --------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

                 United States

- --------------------------------------------------------------------------------
                     5    SOLE VOTING POWER

                                   0 shares

                     -----------------------------------------------------------
     NUMBER OF       6    SHARED VOTING POWER
      SHARES    
   BENEFICIALLY                    2,733,940 shares
     OWNED BY   
       EACH          -----------------------------------------------------------
    REPORTING        7    SOLE DISPOSITIVE POWER
      PERSON 
       WITH                        0 shares

                     -----------------------------------------------------------
                     8    SHARED DISPOSITIVE POWER

                                   2,733,940 shares

- --------------------------------------------------------------------------------
  9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                 2,733,940 shares

- --------------------------------------------------------------------------------
10      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
                                                                             / /

- --------------------------------------------------------------------------------
   11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                 6.26%

- --------------------------------------------------------------------------------
   12   TYPE OF REPORTING PERSON *

                 IN

- --------------------------------------------------------------------------------
                      *SEE INSTRUCTIONS BEFORE FILLING OUT!



                              Page 17 of 39 Pages
<PAGE>   18
- -------------------------                          -----------------------------
CUSIP NO.  0004039171                    13G       PAGE    18  OF  39  PAGES
- -------------------------                          -----------------------------



- --------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

                 Walter G. Kortschak

- --------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                            (a) / /
                                                            (b) / /

- --------------------------------------------------------------------------------
  3     SEC USE ONLY


- --------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

                 United States

- --------------------------------------------------------------------------------
                     5    SOLE VOTING POWER

                                   0 shares

                     -----------------------------------------------------------
     NUMBER OF       6    SHARED VOTING POWER
      SHARES    
   BENEFICIALLY                    2,733,940 shares
     OWNED BY   
       EACH          -----------------------------------------------------------
    REPORTING        7    SOLE DISPOSITIVE POWER
      PERSON 
       WITH                        0 shares

                     -----------------------------------------------------------
                     8    SHARED DISPOSITIVE POWER

                                   2,733,940 shares

- --------------------------------------------------------------------------------
  9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                 2,733,940 shares

- --------------------------------------------------------------------------------
10      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
                                                                             / /

- --------------------------------------------------------------------------------
   11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                 6.26%

- --------------------------------------------------------------------------------
   12   TYPE OF REPORTING PERSON *

                 IN

- --------------------------------------------------------------------------------
                      *SEE INSTRUCTIONS BEFORE FILLING OUT!



                              Page 18 of 39 Pages
<PAGE>   19
- -------------------------                          -----------------------------
CUSIP NO.  0004039171                    13G       PAGE    19  OF  39  PAGES
- -------------------------                          -----------------------------



- --------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

                 Joseph F. Trustey

- --------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                            (a) / /
                                                            (b) / /

- --------------------------------------------------------------------------------
  3     SEC USE ONLY


- --------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

                 United States

- --------------------------------------------------------------------------------
                     5    SOLE VOTING POWER

                                   0 shares

                     -----------------------------------------------------------
     NUMBER OF       6    SHARED VOTING POWER
      SHARES    
   BENEFICIALLY                    1,427,901 shares
     OWNED BY   
       EACH          -----------------------------------------------------------
    REPORTING        7    SOLE DISPOSITIVE POWER
      PERSON 
       WITH                        0 shares

                     -----------------------------------------------------------
                     8    SHARED DISPOSITIVE POWER

                                   1,427,901 shares

- --------------------------------------------------------------------------------
  9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                 1,427,901 shares

- --------------------------------------------------------------------------------
10      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
                                                                             / /

- --------------------------------------------------------------------------------
   11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                 3.27%

- --------------------------------------------------------------------------------
   12   TYPE OF REPORTING PERSON *

                 IN

- --------------------------------------------------------------------------------
                      *SEE INSTRUCTIONS BEFORE FILLING OUT!


                              Page 19 of 39 Pages
<PAGE>   20
                                  Schedule 13G


Item 1(a).        Name of Issuer:  HMT Technology Corporation

Item 1(b).        Address of Issuer's Principal Executive Offices: 1055 Page
                  Avenue, Fremont, CA 94538


Item 2(a).        Names of Persons Filing: Summit Ventures III, L.P., Summit
                  Partners III, L.P., Summit Ventures IV, L.P., Summit Partners
                  IV, L.P., Summit Partners SD, L.P, Summit Subordinated Debt
                  Fund, L.P., Summit Investors II, L.P., Stamps, Woodsum & Co.
                  III, Stamps, Woodsum & Co. IV, and Messrs. E. Roe Stamps, IV,
                  Stephen G. Woodsum, Gregory M. Avis, John A. Genest, Martin J.
                  Mannion, Bruce R. Evans, Thomas S. Roberts, Walter G.
                  Kortschak and Joseph F. Trustey.

                  Summit Partners III, L.P. is the sole general partner of
                  Summit Ventures III, L.P. Summit Partners IV, L.P. is the sole
                  general partner of Summit Ventures IV, L.P. Summit Partners
                  SD, L.P. is the sole general partner of Summit Subordinated
                  Debt Fund, L.P. Stamps, Woodsum & Co. III is the sole general
                  partner of Summit Partners III, L.P. Stamps, Woodsum & Co. IV
                  is the sole general partner of Summit Partners IV, L.P.
                  Stamps, Woodsum & Co. III is the sole general partner of
                  Summit Partners SD, L.P. Messrs. Stamps, Woodsum, Avis,
                  Genest, Mannion, Evans, Roberts and Kortschak are individual
                  general partners of Stamps, Woodsum & Co. III, Stamps, Woodsum
                  & Co. IV and Summit Investors II, L.P. Messr. Trustey is an
                  individual general partner of Stamps, Woodsum & Co. III, and
                  Stamps, Woodsum & Co. IV.

                  As of December 31, 1998, Ernest K. Jacquet was no longer
                  affiliated with any of the "Entities" (as defined below).

Item 2(b).        Address of Principal Business Office or, if None, Residence:
                  The address of the principal business office of Summit
                  Ventures III, L.P., Summit Ventures IV, L.P., Summit
                  Subordinated Debt Fund, L.P., Summit Investors II, L.P.,
                  Summit Partners III, L.P., Summit Partners IV, L.P., Summit
                  Partners SD, L.P., Stamps, Woodsum & Co. III, Stamps, Woodsum
                  & Co. IV, and Messrs. Stamps, Woodsum, Mannion, Genest, Evans,
                  Roberts and Trustey is Summit Partners, 600 Atlantic Avenue,
                  Boston, Massachusetts 02210. The address of the principal
                  business office of Messrs. Avis and Kortschak is Summit
                  Partners, 499 Hamilton Avenue, Palo Alto, California 94301.

Item 2(c).        Citizenship: Each of Summit Ventures III, L.P., Summit
                  Partners III, L.P., Summit Ventures IV, L.P., Summit Partners
                  IV, L.P., Summit Investors II, L.P., Summit Subordinated Debt
                  Fund, L.P. and Summit Partners SD, L.P. is a limited
                  partnership organized under the laws of the State of Delaware.
                  Each of Stamps, Woodsum & Co. III and Stamps, Woodsum & Co. IV
                  is a general partnership 



                              Page 20 of 39 Pages
<PAGE>   21

                  organized under the laws of the Commonwealth of Massachusetts.
                  Each of Messrs. Stamps, Woodsum, Avis, Mannion, Genest, Evans,
                  Roberts, Kortschak and Trustey is a United States citizen.

Item 2(d).        Title of Class of Securities: Common Stock, $.001 par value
                  per share.

Item 2(e).        CUSIP Number: 403917107

Item 3.           If this statement is filed pursuant to Rules 13d-1(b), or
                  13d-2(b), check whether the person filing is a:


                  Not Applicable

Item 4.           Ownership.

                  (a)   Amount Beneficially Owned:

                        Each of Summit Ventures IV, L.P., Summit Partners IV,
                        L.P., Summit Ventures III, L.P., Summit Partners III,
                        L.P., Summit Investors II, L.P., Stamps, Woodsum & Co.
                        IV, Stamps, Woodsum & Co. III, Summit Subordinated Debt
                        Fund, L.P. and Summit Partners SD, L.P. (individually an
                        "Entity" and collectively the "Entities") may be deemed
                        to own beneficially 2,733,940 shares of Common Stock as
                        of December 31, 1998. Each of Messrs. Stamps, Woodsum,
                        Avis, Mannion, Genest, Evans, Roberts and Kortschak may
                        be deemed to own beneficially 2,733,940 shares of Common
                        Stock as of December 31, 1998. Mr. Trustey may be deemed
                        to own 1,427,901 shares of Common Stock as of December
                        31, 1998.

                        As of December 31, 1998, Summit Ventures III, L.P. was
                        the record owner of 1,258,902 shares of Common Stock. As
                        of December 31, 1998, Summit Investors II, L.P. was the
                        record owner of 47,137 shares of Common Stock. As of
                        December 31, 1998, Summit Ventures IV, L.P. was the
                        record owner of 1,258,902 shares of Common Stock. As of
                        December 31, 1998, Summit Subordinated Debt Fund, L.P.
                        was the record owner of 168,999 shares of Common Stock.
                        The shares held of record by Summit Ventures III, L.P.,
                        Summit Investors II, L.P., Summit Ventures IV, L.P. and
                        Summit Subordinated Debt Fund, L.P. are referred to
                        herein collectively as the "Record Shares." By virtue of
                        the affiliate relationships among the Entities, each
                        Entity may be deemed to own beneficially all of the
                        Record Shares. Hence, each Entity may be deemed to own
                        beneficially 2,733,940 shares of Common Stock. In their
                        capacities as individual general partners of Stamps,
                        Woodsum & Co. III, Stamps, Woodsum & Co. IV, and Summit
                        Investors II, L.P., each of Messrs. Stamps, Woodsum,
                        Avis, Mannion, Genest, Evans, Roberts and Kortschak may
                        be deemed to own beneficially 2,733,940 shares of Common
                        Stock. In his capacity as individual general partner of
                        Stamps,



                              Page 21 of 39 Pages
<PAGE>   22

                        Woodsum & Co. III and Stamps, Woodsum & Co. IV, Mr.
                        Trustey may be deemed to own beneficially 1,427,901
                        shares of Common Stock.

                        Each of the reporting persons expressly disclaims
                        beneficial ownership of any shares of Common Stock of
                        HMT Technology Corporation, except in the case of Summit
                        Ventures IV, L.P., for the 1,258,902 shares which it
                        holds of record, in the case of Summit Subordinated Debt
                        Fund, L.P., for the 168,999 shares which it holds of
                        record, in the case of Summit Investors II, L.P., for
                        the 47,137 shares which it holds of record, and in the
                        case of Summit Ventures III, L.P., for the 1,258,902
                        shares which it holds of record.

                    (b) Percent of Class:

                        Summit Ventures II, L.P.:  6.26%
                        Summit Partners II, L.P.:  6.26%
                        Summit Ventures III, L.P.:  6.26%
                        Summit Partners III, L.P.:  6.26%
                        Summit Subordinated Debt Fund, L.P.:  6.26%
                        Summit Partners SD, L.P.:  6.26%
                        Summit Investors II, L.P.:  6.26%
                        Stamps, Woodsum & Co. III:  6.26%
                        Stamps, Woodsum & Co. IV:  6.26%
                        E. Roe Stamps, IV:  6.26%
                        Stephen G. Woodsum:  6.26%
                        Gregory M. Avis:  6.26%
                        Martin J. Mannion:  6.26%
                        John A. Genest:  6.26%
                        Bruce R. Evans:  6.26%
                        Walter G. Kortschak:  6.26%
                        Thomas S. Roberts: 6.26%
                        Joseph F. Trustey:  3.27%

                        The foregoing percentages are calculated based on the
                        43,682,577 shares of Common Stock reported to be
                        outstanding in a Quarterly Report on Form 10-Q/A for HMT
                        Technology Corporation for the quarterly period ended
                        September 30, 1998.

                    (c) Number of shares as to which such person has:

                        (i)    sole power to vote or to direct the vote:

                               0 shares for each reporting person

                       (ii)    shared power to vote or to direct the vote:


                              Page 22 of 39 Pages
<PAGE>   23


                           Summit Ventures III, L.P.: 2,733,940 shares
                           Summit Partners III, L.P.: 2,733,940 shares
                           Summit Ventures IV, L.P.:  2,733,940 shares
                           Summit Partners IV, L.P.: 2,733,940 shares
                           Summit Subordinated Debt Fund, L.P. 2,733,940 shares
                           Summit Partners SD, L.P.: 2,733,940 shares
                           Summit Investors II, L.P.:  2,733,940 shares
                           Stamps, Woodsum & Co. III:  2,733,940 shares
                           Stamps, Woodsum & Co. IV:  2,733,940 shares
                           E. Roe Stamps, IV:  2,733,940 shares
                           Stephen G. Woodsum:  2,733,940 shares
                           Gregory M. Avis:  2,733,940 shares
                           Martin J. Mannion:  2,733,940 shares
                           John A. Genest:  2,733,940 shares
                           Bruce R. Evans:  2,733,940 shares
                           Walter G. Kortschak:  2,733,940 shares
                           Thomas S. Roberts: 2,733,940 shares
                           Joseph F. Trustey: 1,427,901 shares

                     (iii) sole power to dispose or direct the disposition of:

                              0 shares for each reporting person

                      (iv) shared power to dispose or direct the disposition
                           of:

                           Summit Ventures III, L.P.: 2,733,940 shares
                           Summit Partners III, L.P.: 2,733,940 shares
                           Summit Ventures IV, L.P.:  2,733,940 shares
                           Summit Partners IV, L.P.: 2,733,940 shares
                           Summit Subordinated Debt Fund, L.P.: 2,733,940 shares
                           Summit Partners SD, L.P.: 2,733,940 shares
                           Summit Investors II, L.P.:  2,733,940 shares
                           Stamps, Woodsum & Co. III:  2,733,940 shares
                           Stamps, Woodsum & Co. IV:  2,733,940 shares
                           E. Roe Stamps, IV:  2,733,940 shares
                           Stephen G. Woodsum:  2,733,940 shares
                           Gregory M. Avis:  2,733,940 shares
                           Martin J. Mannion:  2,733,940 shares
                           John A. Genest:  2,733,940 shares
                           Bruce R. Evans:  2,733,940 shares
                           Walter G. Kortschak:  2,733,940 shares
                           Thomas S. Roberts:  2,733,940 shares
                           Joseph F. Trustey:  1,427,901 shares

Item 5.           Ownership of Five Percent or Less of a Class.

                              Page 23 of 39 Pages
<PAGE>   24

                  [ X ] Mr. Trustey may be deemed to own beneficially 1,427,901
                  shares of Common Stock as of December 31, 1998, which is five
                  percent or less of the Common Stock of HMT Technology
                  Corporation.

Item 6.           Ownership of More than Five Percent on Behalf of Another
                  Person.

                  Not Applicable.

Item 7.           Identification and Classification of the Subsidiary which
                  Acquired the Security Being Reported on By the Parent Holding
                  Company.

                  Not Applicable.

Item 8.           Identification and Classification of Members of the Group.

                  Not Applicable. The reporting persons expressly disclaim
                  membership in a "group" as defined in Rule 13d-1(b)(ii)(H).

Item 9.           Notice of Dissolution of Group.

                  Not Applicable.

Item 10.          Certification.

                  Not Applicable. This statement on Schedule 13G is not filed
                  pursuant to Rule 13d-1(b).


                              Page 24 of 39 Pages
<PAGE>   25

                                   SIGNATURES

      After reasonable inquiry and to the best of our knowledge and belief, we
certify that the information set forth in this statement is true, complete and
correct. We also hereby agree to file this statement jointly pursuant to the
Agreement listed on Exhibit 1 hereto.

Dated:  February 10, 1999

SUMMIT VENTURES IV, L.P.                          SUMMIT INVESTORS II, L.P.

By:   Summit Partners IV, L.P.                    By: /s/ John A. Genest
                                                     -------------------------
                                                        General Partner
By:   Stamps, Woodsum & Co. IV
                                                  SUMMIT PARTNERS IV, L.P.
      By:          *
          ------------------------
              E. Roe Stamps, IV                   By:  Stamps, Woodsum & Co. IV
              General Partner
                                                        By:       *
SUMMIT VENTURES III, L.P.                                 --------------------
                                                            E. Roe Stamps, IV
                                                            General Partner
By:   Summit Partners III, L.P.
                                                  SUMMIT PARTNERS III, L.P.
By:   Stamps, Woodsum & Co. III
                                                  By: Stamps, Woodsum & Co. III
      By:          *
          -------------------------
              E. Roe Stamps, IV                         By:      *
              General Partner                              -------------------
                                                            E. Roe Stamps, IV
                                                            General Partner
SUMMIT SUBORDINATED DEBT FUND, L.P.
                                                  SUMMIT PARTNERS SD, L.P.
By:   Summit Partners SD, L.P.
                                                  By: Stamps, Woodsum & Co. III
By:   Stamps, Woodsum & Co. III
                                                        By:       *
             By:      *                                    -------------------
               ----------------------                       E. Roe Stamps, IV
              E. Roe Stamps, IV                             General Partner
              General Partner


                              Page 25 of 39 Pages
<PAGE>   26



STAMPS, WOODSUM & CO. IV                          STAMPS, WOODSUM & CO. III

By:          *                                   By:         *
     ------------------------                      ---------------------------
      E. Roe Stamps, IV                            E. Roe Stamps, IV
      General Partner                              General Partner

             *                                                *
     ------------------------                      ---------------------------
      E. Roe Stamps, IV                            Martin J. Mannion

             *                                      /s/ John A. Genest
     ------------------------                      ---------------------------
     Stephen G. Woodsum                            John A. Genest

              *                                              *
     ------------------------                      ---------------------------
     Gregory M. Avis                               Bruce R. Evans

              *                                              *
     ------------------------                      ---------------------------
     Joseph F. Trustey                             Walter G. Kortschak

                                                             *
                                                   ---------------------------
                                                   Thomas S. Roberts

                                                             *
                                                   ---------------------------
                                                   Joseph F. Trustey

                                                  *By: /s/ John A. Genest
                                                   ---------------------------
                                                        John A. Genest,
                                                        Attorney-in-fact


- ----------
* Pursuant to Powers of Attorney on file with the Commission, which Powers of
Attorney are incorporated herein by reference. Copies of such Powers of Attorney
are attached hereto as Exhibit 2.


                              Page 26 of 39 Pages

<PAGE>   1


                                                                       Exhibit 1

                                    AGREEMENT

      Pursuant to Rule 13d-1(f)(1) under the Securities Exchange Act of 1934,
the undersigned hereby agree that only one statement containing the information
required by Schedule 13G need be filed with respect to the ownership by each of
the undersigned of shares of Common Stock of HMT Technology Corporation.

      This agreement may be executed in any number of counterparts, each of
which shall be deemed an original.

      EXECUTED this 10th day of February, 1999.

SUMMIT VENTURES IV, L.P.                           SUMMIT INVESTORS II, L.P.

By:   Summit Partners IV, L.P.                     By:  /s/ John A. Genest
                                                       ------------------------
                                                         General Partner
By:   Stamps, Woodsum & Co. IV
                                                   SUMMIT PARTNERS IV, L.P.
      By:                   *
         -------------------------
              E. Roe Stamps, IV                    By: Stamps, Woodsum & Co. IV
              General Partner
                                                         By:      *
SUMMIT VENTURES III, L.P.                                  --------------------
                                                            E. Roe Stamps, IV
                                                            General Partner
By:   Summit Partners III, L.P.
                                                   SUMMIT PARTNERS III, L.P.
By:   Stamps, Woodsum & Co. III
                                                   By: Stamps, Woodsum & Co. III
      By:           *
          ---------------------
              E. Roe Stamps, IV                          By:       *
              General Partner                               -------------------
                                                            E. Roe Stamps, IV
                                                            General Partner
SUMMIT SUBORDINATED DEBT FUND, L.P.
                                                   SUMMIT PARTNERS SD, L.P.
By:   Summit Partners SD, L.P.
                                                   By: Stamps, Woodsum & Co. III
By:   Stamps, Woodsum & Co. III
                                                         By:       * 
                                                            -------------------
      By:            *                                      E. Roe Stamps, IV
        ------------------------                            General Partner
              E. Roe Stamps, IV                             
              General Partner


                              Page 27 of 39 Pages
<PAGE>   2

STAMPS, WOODSUM & CO. III                                 *
                                                   ---------------------------
                                                   E. Roe Stamps, IV

By:                 *                                     *
     ---------------------                        -----------------------------
         E. Roe Stamps, IV                         Stephen G. Woodsum
         General Partner
                                                          *
                                                   ----------------------------
                                                   Gregory M. Avis
STAMPS, WOODSUM & CO. IV
                                                          *
                                                   ---------------------------
By:                *                               Martin J. Mannion
    ----------------------                              
      E. Roe Stamps, IV                             /s/ John A. Genest
      General Partner                              ----------------------------
                                                   John A. Genest

                                                           *
                                                   ---------------------------
                                                   Bruce R. Evans

                                                           *
                                                   ---------------------------
                                                   Walter G. Kortschak

                                                           *
                                                   ---------------------------
                                                   Thomas S. Roberts

                                                           *
                                                   ---------------------------
                                                   Joseph F. Trustey


                              Page 28 of 39 Pages
<PAGE>   3



                                                   *By: /s/ John A. Genest
                                                       -----------------------
                                                         John A. Genest,
                                                         Attorney-in-fact
- ----------
*     Pursuant to Powers of Attorney on file with the Commission, which Powers
      of Attorney are incorporated herein by reference. Copies of such Powers of
      Attorney are attached hereto as Exhibit 2.



                              Page 29 of 39 Pages

<PAGE>   1


                                                                       Exhibit 2

                                POWER OF ATTORNEY


         KNOW ALL MEN BY THESE PRESENTS, that each person whose signature
appears below hereby constitutes and appoints each and any of E. Roe Stamps, IV,
Stephen G. Woodsum and John A. Genest his true and lawful attorney-in-fact and
agent, with full power of substitution and resubstitution, for him and in his
name, place and stead, in any and all capacities (until revoked in writing) to
sign any and all instruments, certificates and documents required to be executed
on behalf of himself individually or on behalf of each or any of Summit
Ventures, L.P., Summit Partners, L.P., Stamps, Woodsum & Co., Summit Partners'
Holdings, L.P., Summit Ventures II, L.P., Summit Partners II, L.P., Stamps,
Woodsum & Co. II, SV Eurofund C.V., SV International, L.P., Stamps, Woodsum
International & Co., Summit Investors, L.P., Summit Investors II, L.P., Summit
Investors III, L.P., Summit Ventures III, L.P., Summit Partners III, L.P.,
Stamps, Woodsum & Co. III, Summit Ventures IV, L.P., Summit Partners IV, L.P.,
Stamps, Woodsum & Co., IV, Summit Subordinated Debt Fund, L.P., Summit Partners
SD, L.P., SW Management Corp., Summit Management Co., Summit Subordinated Debt
Fund II, L.P., and Summit Partners SD II, LLC, pursuant to sections 13 and 16 of
the Securities Exchange Act of 1934, as amended (the "Exchange Act"), and any
and all regulations promulgated thereunder, and to file the same, with all
exhibits thereto, and any other documents in connection therewith, with the
Securities and Exchange Commission, and with any other entity when and if such
is mandated by the Exchange Act or by the By-laws of the National Association of
Securities Dealers, granting unto said attorney-in-fact and agent full power and
authority to do and perform each and every act and thing requisite and necessary
fully to all intents and purposes as she might or could do in person thereby
ratifying and confirming all that said attorney-in-fact and agent, or her
substitute or substitutes, may lawfully do or cause to be done by virtue hereof.


                              Page 30 of 39 Pages
<PAGE>   2
         IN WITNESS WHEREOF, this Power of Attorney has been signed as of the
10th day of February, 1997.


                                       /s/  E. Roe Stamps, IV
                                       -----------------------------------------
                                       E. Roe Stamps, IV


Commonwealth of Massachusetts     )
                                  ) ss:
County of Suffolk                 )

         On this 10th day of February, 1997, before me personally came E. Roe
Stamps, IV, known to me to be the person described and who executed the
foregoing instrument that he acknowledged that he executed the same.

[Notary Seal]

                                       /s/  Cynthia R. Freidman
                                       -----------------------------------------
                                       Notary Public


                                       My Commission expires:  October 20, 2000


                              Page 31 of 39 Pages
<PAGE>   3
         IN WITNESS WHEREOF, this Power of Attorney has been signed as of the
10th day of February, 1997.


                                       /s/  Stephen G. Woodsum
                                       -----------------------------------------
                                       Stephen G. Woodsum


Commonwealth of Massachusetts     )
                                  ) ss:
County of Suffolk                 )

         On this 10th day of February, 1997, before me personally came Stephen 
G. Woodsum, known to me to be the person described and who executed the
foregoing instrument that he acknowledged that he executed the same.

[Notary Seal]

                                       /s/  Cynthia R. Freidman
                                       -----------------------------------------
                                       Notary Public


                                       My Commission expires:  October 20, 2000


                              Page 32 of 39 Pages
<PAGE>   4
         IN WITNESS WHEREOF, this Power of Attorney has been signed as of the
10th day of February, 1997.


                                       /s/  Martin J. Mannion
                                       -----------------------------------------
                                       Martin J. Mannion


Commonwealth of Massachusetts     )
                                  ) ss:
County of Suffolk                 )

         On this 10th day of February, 1997, before me personally came Martin 
J. Mannion, known to me to be the person described and who executed the
foregoing instrument that he acknowledged that he executed the same.

[Notary Seal]

                                       /s/  Cynthia R. Freidman
                                       -----------------------------------------
                                       Notary Public


                                       My Commission expires:  October 20, 2000


                              Page 33 of 39 Pages
<PAGE>   5
         IN WITNESS WHEREOF, this Power of Attorney has been signed as of the
10th day of February, 1997.


                                       /s/  John A. Genest
                                       -----------------------------------------
                                       John A. Genest


Commonwealth of Massachusetts     )
                                  ) ss:
County of Suffolk                 )

         On this 10th day of February, 1997, before me personally came John A. 
Genest, known to me to be the person described and who executed the foregoing 
instrument that he acknowledged that he executed the same.

[Notary Seal]

                                       /s/  Cynthia R. Freidman
                                       -----------------------------------------
                                       Notary Public


                                       My Commission expires:  October 20, 2000


                              Page 34 of 39 Pages
<PAGE>   6
         IN WITNESS WHEREOF, this Power of Attorney has been signed as of the
10th day of February, 1997.


                                       /s/  Gregory M. Avis
                                       -----------------------------------------
                                       Gregory M. Avis


State of California          )
                             ) ss:
County of Santa Clara        )

         On this 3rd day of February, 1997, before me personally came Stephen G.
Woodsum, known to me to be the person described and who executed the foregoing
instrument that he acknowledged that he executed the same.

[Notary Seal]

                                       /s/ Katherine C. Ely
                                       -----------------------------------------
                                       Notary Public


                                       My Commission expires:  May 28, 2000


                              Page 35 of 39 Pages
<PAGE>   7
         IN WITNESS WHEREOF, this Power of Attorney has been signed as of the
10th day of February, 1997.


                                       /s/  Thomas S. Roberts
                                       -----------------------------------------
                                       Thomas S. Roberts


Commonwealth of Massachusetts     )
                                  ) ss:
County of Suffolk                 )

         On this 10th day of February, 1997, before me personally came Thomas 
S. Roberts, known to me to be the person described and who executed the
foregoing instrument that he acknowledged that he executed the same.

[Notary Seal]

                                       /s/  Cynthia R. Freidman
                                       -----------------------------------------
                                       Notary Public


                                       My Commission expires:  October 20, 2000


                              Page 36 of 39 Pages
<PAGE>   8
         IN WITNESS WHEREOF, this Power of Attorney has been signed as of the
10th day of February, 1997.


                                       /s/  Bruce R. Evans
                                       -----------------------------------------
                                       Bruce R. Evans


Commonwealth of Massachusetts     )
                                  ) ss:
County of Suffolk                 )

         On this 10th day of February, 1997, before me personally came Bruce R. 
Evans, known to me to be the person described and who executed the
foregoing instrument that he acknowledged that he executed the same.

[Notary Seal]

                                       /s/  Cynthia R. Freidman
                                       -----------------------------------------
                                       Notary Public


                                       My Commission expires:  October 20, 2000


                              Page 37 of 39 Pages
<PAGE>   9
         IN WITNESS WHEREOF, this Power of Attorney has been signed as of the
10th day of February, 1997.


                                       /s/  Walter G. Kortschak
                                       -----------------------------------------
                                       Walter G. Kortschak


State of California          )
                             ) ss:
County of Santa Clara        )

         On this 3rd day of February, 1997, before me personally came Walter G.
Kortschak, known to me to be the person described and who executed the foregoing
instrument that he acknowledged that he executed the same.


[Notary Seal]

                                       /s/ Katherine C. Ely
                                       -----------------------------------------
                                       Notary Public


                                       My Commission expires:  May 28, 2000


                              Page 38 of 39 Pages
<PAGE>   10
         IN WITNESS WHEREOF, this Power of Attorney has been signed as of the
10th day of February, 1997.


                                       /s/  Joseph F. Trustey
                                       -----------------------------------------
                                       Joseph F. Trustey


Commonwealth of Massachusetts     )
                                  ) ss:
County of Suffolk                 )

         On this 10th day of February, 1997, before me personally came Joseph F.
Trustey, known to me to be the person described and who executed the foregoing
instrument that he acknowledged that he executed the same.

[Notary Seal]


                                       /s/  Cynthia R. Freidman
                                       -----------------------------------------
                                       Notary Public


                                       My Commission expires:  October 20, 2000



                              Page 39 of 39 Pages


© 2022 IncJournal is not affiliated with or endorsed by the U.S. Securities and Exchange Commission