STUTTGART, Germany - The families who control Porsche are open to the idea of selling a stake to an outside investor, the company said Wednesday.

Porsche shares shot up on the news, which was first reported by Focus Online magazine. Shares were trading at 43.42 euros, up 5.1 percent, by 1214 GMT.

The Porsche and Piech families stand united behind the idea of a possible stake sale to an outside investor, a Porsche spokesman told Reuters.

The emirate of Quatar has in the past expressed an interest in Porsche.

Porsche has sought financial allies for its struggle to bolster its finances after running up 9 billion euros ($12.27 billion) in debt while building a 51 percent stake in Volkswagen (VOWG.DE).

(Reporting by Hendrik Sackmann)

($1=.7334 Euro)