Create a portfolio table from a buy and sell table

Hi All,

I have the following data that I put in to the table:

This table contains Companies (PortfolioID) that are sold or bought by a PE Houses (Seller and Buyer). I would like to create a Portfolio table which contains only Buyers who did not sell a company and holds it. E.g.: the company 1111 should not be shown in portfolio of the PE House 6112. (bought in the first row and sold in the last row).

Any ideas how can I solved this Power Bi?

Thx