You can search for insider holdings through Thomson Reuters Ownership Database in WRDS. 

Please note: Thomson Reuters Ownership data (formerly called Spectrum) is not a clean set of data. This is mostly due to reporting inconsistencies with the SEC documents from which the data is pulled. Also, this is a database of transactions (buying and selling of stock) so it is meant to be a record of changes in position, not a snapshot by quarter.

Choose Database

• Select Thomson Reuters
• Under Insiders Data on left select Table 1. Stock Transactions

Step One: Date Range

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

Step Two: Search

• Set code format to CUSIP6
• Click Code lookup under Manually enter insider codes; a new window will open
• Type company name, e.g. General Electric, into search box; click Starts with
• Copy and paste the company's CUSIP6 back into the Company Codes box on the main WRDS search page
• Enter multiple codes by leaving a single space between them
• Change All Records drop down box to Exclude Problematic Records
• Leave all other boxes in this step as is

Step Three: Variables

• In Insider Information check Owner Full Name & Role Code 1
• In Company Information check Company Name & CUSIP Issuer (6 chars)
• In Transaction Information check Ownership Type, Resulted Shares Held, Resulted Shares Held Adjusted and Security Title
• 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