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                                            Filed by Komag, Incorporated
                                            Pursuant to Rule 425 under the
                                            Securities Act of 1933, and deemed
                                            filed pursuant to Rule 14a-12 under
                                            the Securities and Exchange Act of
                                            1934. Subject Company:
                                            HMT Technology Corporation
                                            Commission File No. 333-39340


                              KOMAG, INCORPORATED
                  PRESS RELEASE ISSUED ON SEPTEMBER 20, 2000


                      KOMAG STOCKHOLDERS APPROVE HMT MERGER

FOR IMMEDIATE RELEASE

SAN JOSE, Calif., September 20, 2000 /PRNewswire/ -- Komag, Incorporated
(Nasdaq: KMAG), a technical leader in the disk drive component industry, today
announced that its stockholders approved the issuance of Komag common stock in
the previously announced merger of a wholly owned subsidiary of Komag with and
into HMT Technology Corporation ("HMT"). HMT would become a wholly-owned
subsidiary of Komag as a result of the merger. The companies anticipate closing
the merger on October 2, 2000.

ADDITIONAL INFORMATION AND WHERE TO FIND IT

Komag has filed a Registration Statement on SEC Form S-4 in connection with the
merger. Investors and security holders are urged to read the Registration
Statement and the Joint Proxy Statement/Prospectus carefully. The Registration
Statement and the Joint Proxy Statement/Prospectus contain important information
about Komag, HMT, the merger and related matters. Investors and security holders
will be able to obtain free copies of these documents through the website
maintained by the U.S. Securities and Exchange Commission at http://www.sec.gov.
Free copies of the Joint Proxy Statement/Prospectus and these other documents
may also be obtained from Komag by directing a request through the Investor
Relations portion of Komag's website at http://www.komag.com or by mail to
Komag, Incorporated, 1710 Automation Parkway, San Jose, CA 95131, attention:
Investor Relations, telephone: (408) 576-2000.

In addition to the Registration Statement and the Joint Proxy
Statement/Prospectus, Komag and HMT file annual, quarterly and special reports,
proxy statements and other information with the Securities and Exchange
Commission. You may read and copy any reports, statements or other information
filed by Komag or HMT at the SEC public reference rooms at 450 Fifth Street,
N.W., Washington, D.C. 20549 or at any of the Commission's other public
reference rooms in New York, New York and Chicago, Illinois. Please call the
Commission at 1-800-SEC-0330 for further information on the public reference
rooms. Komag's and HMT's filings with the Commission are also available to the
public from commercial document-retrieval services and at the website maintained
by the Commission at http://www.sec.gov.

FORWARD-LOOKING STATEMENTS

The above information contains a forward-looking statement about closing the
merger that may involve risks and uncertainties. While this outlook represents
Komag's current judgment, there can be no assurance that the merger will be
completed on schedule or at all. This and other risk factors are described in
the most recent Form 10-Q, most recent Form 10-K and other periodic reports
filed by Komag and HMT with the Securities and Exchange Commission.


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ABOUT KOMAG:

Founded in 1983, Komag, Incorporated has produced over 465 million thin-film
disks, the primary storage medium for digital data used in computer disk drives.
The company is well positioned as the broad-based strategic supplier of choice
for the industry's leading disk drive manufacturers. Through its advanced
development facilities in the United States and high volume production factories
in Southeast Asia, Komag provides high quality, leading-edge disk products at a
low overall cost to its customers. These attributes enable Komag to partner with
customers in the execution of their time-to-market design and time-to-volume
manufacturing strategies.

For more information about Komag, visit Komag's Internet home page at
http://www.komag.com or call Komag's Investor Relations 24-hour Hot Line at
888-66-KOMAG or 408-576-2901.

Contact:          KOMAG, INCORPORATED, San Jose, CA
                  Ted Siegler at (408) 576-2209
                  E-mail communications: ir_web@komag.com