Sports carmaker Porsche AG — currently owned by Volkswagen (VW) — is planning to go public on the Frankfurt Stock Exchange, expected at the end of September or the start of October.

With an expected market value of up to $60-85B — this could become one of Europe’s largest IPOs.

Bad blood: Porsche and Volkswagen go way back to their origin. Porsche’s founder and a top VW exec were cousins, and competition runs in their blood…

• In 2005, Porsche started buying VW shares with the goal of gaining full control.
• But the 2008 financial crisis hit, and VW acquired Porsche instead. In a complex corporate structure, Porsche retained majority voting control of VW.

Porsche became Volkswagen’s cash cow — accelerating in the recent quarter as Porsche’s operating income rose 22% while Volkswagen’s fell 8%.

More power: “This is effectively a family business,” and outside investors are getting non-voting shares — per European autos analyst Michael Dean (BBG).

• After the IPO, the Porsche family will have the power to veto major strategic decisions.
• Making matters worse, the current CEO of VW, Oliver Blume, has become the CEO of both Porsche and Volkswagen (alert: conflict of interest).

With Porsche and Volkswagen undergoing a major scandal for cheating emissions tests in recent years, poor corporate governance is the last thing you want to see.