You can search for institutional holdings through Thomson Reuters in WRDS. 

Please note: Thomson Reuters institutional data (formerly called Spectrum) is based on the actions of money managers of institutions holding stock. It does not focus on the companies issuing the stock. CUSIPs for the companies issuing the stocks must be looked up beforehand in the CRSP database on WRDS and then used in the Thomson database. CUSIPs are not available through the Code Lookup feature.

Search for CUSIPs

• Look up CUSIPs for issuing companies in CRSP

Choose Database

• Select Thomson Reuters
• Under Institutional (13f) Holdings - s34 on left select s34 Master File

Step One: Date Range

• Set Beginning Date month and year
• Set Ending Date month and year

Step Two: Search

• Set code format to CUSIP
• Copy and paste the CUSIPs you have already looked up into the Company Codes box under Manually enter insider codes
• Enter multiple codes by leaving a single space between them
• Leave all other boxes in this step as is

Step Three: Variables

• In Manager Description Information check Manager Name
• In Holdings Information check Company Name and Shares Held
• Leave all other boxes in this step as is.

Step Four: Output

• Choose Tab-delimited text (*.txt) format
• Leave all other boxes in this step as is
• Click Submit Query 
• Data Request Summary window will open
• Right mouse click on the highlighted file name
• Choose Save Target As option
• Save as a .txt file to your computer
• Open file in Excel