Use Bloomberg, available in the Margolis Market Information Lab (MIL) at the Business Instructional Facility (BIF).

Examples:
IBM [EQUITY] hds [GO]
*Click on Advanced Filter and check Display Market Value of Position to get the dollar amount of holdings instead of the percentage of shares held.
For statistics:
IBM [EQUITY] des4 [GO]
Search companies alphabetically or by size of holdings:
IBM [EQUITY] phdcs [GO]