Porsche AG on Thursday said it had bought 32,868,462 Volkswagen AG common shares, for a 10.26% stake.

Earlier this week, the sports car specialist said it would acquire a VW stake of about 20%.

"Porsche intends to gain representation on the VW supervisory board in line with the planned level of participation," it said in a statement on Thursday.

Press reports said Porsche wouldn't reveal how it acquired the shares and had not bought any of the 13% VW owns in the sports car maker.

There is speculation that hedge funds or other recent short-term investors have sold out, or that one or more of the big strategic US shareholders has sold part of its shareholding.

Industry observers will now be eyeing how Porsche builds its holding to 20%, financial commentators noted.

Golding's take

Stake won't break bank