The Canadian luxury retailer priced its IPO at $12.78 a share on Wednesday and opened for trading at $18 Thursday.
PETA said it had bought 230 shares in order to submit shareholder resolutions and speak at annual shareholder meetings. It was not immediately clear at what price or on which exchange the organization bought in.
"PETA's first order of business as part owner of Canada Goose? To pressure the company to stop using fur from cruelly trapped coyotes and down feathers from slaughtered geese," the company said in a statement.
The animal rights group on Wednesday told Yahoo it wanted to buy $4,000 worth of shares.
PETA also staged protests in New York and Toronto on Thursday.