Porsche SE's controlling shareholders, the Porsche and Piech families, will meet in Salzburg, Austria today to hash out how to combine the sports-car maker with Volkswagen AG and reduce 9 billion euros ($12 billion) of debt, according to people familiar with the matter.

The proposals under consideration include merging the carmakers and finding an investor to buy a stake in the combined company or selling the Porsche AG automotive unit to Volkswagen in return for cash and shares, said one of the people, who declined to be identified because the talks are private.

"Structural changes in Porsche's makeup are inevitable," said Marc-Rene Tonn of M.M. Warburg in Hamburg who recommends buying Porsche shares and selling Volkswagen. "No one at the Porsche-Piech families is under any illusions about the size of the debt."