PRINCIPAL OWNERSHIP
                      OF VITESSE SEMICONDUCTOR CORPORATION
                                  COMMON STOCK
 
   The following table shows the number of shares of Company common stock owned
as of September 30, 1999 by the directors, the Named Executive Officers listed 
on page 13, all directors and officers as a group, and holders known to the
Company of at least 5% of the Company's common stock.
 
                         Principal Stock Ownership(/1/)
 

                                                           Total Shares
                                           Shares       Beneficially Owned
                                         Exercisable     Plus Exercisable
Name of Individuals or   Shares Owned Within 60 Days of Within 60 Days of  Percent
Identity of Group        Beneficially  Sept. 30, 1999     Sept. 30, 1999   of Total
----------------------   ------------ ----------------- ------------------ --------
                                                               
Fidelity Management and
 Research Corporation
 82 Devonshire Street
 Boston, MA 02109-3614..  12,400,000            --          12,400,000       7.9%

Janus Capital
 Corporation
 100 Fillmore Street
 Denver, CO 80206-4928..   9,678,340            --           9,678,340       6.2%

Louis R.
 Tomasetta(/2/).........     694,036        402,312          1,096,348         *
Neil J. Rappaport.......      70,812        280,000            350,812         *
Pierre R. Lamond........     160,000         75,600            235,600         *
James A. Cole...........      33,700        176,400            210,100         *
Christopher Gardner.....      46,904        110,000            156,904         *
John C. Lewis...........      70,000         45,600            115,600         *
Michael Millhollan......      16,570         70,620             87,190         *
Eugene F. Hovanec.......      10,596         52,338             62,934         *
Alex Daly...............           0         38,400             38,400         *

All executive officers
 and directors as a
 group (12 persons).....   1,531,058      1,441,804          2,972,862       1.9%

--------

 *    Less than 1%

(/1/) All share information has been adjusted to reflect a 3 for 2 stock split
      on February 12, 1997, a 2 for 1 stock split on May 26, 1998, and a 2 for
      1 stock split on October 20, 1999.

(/2/) Includes an aggregate of 63,000 shares held for each of Kathleen A. and
      Susan A. Tomasetta, pursuant to the Transfer to Minors Act and as to
      which Dr. Tomasetta has voting and investment power.