Porsche has increased its stake in Volkswagen, saying it hopes to have a majority holding in Europe's biggest carmaker by the end of the year.
Porsche revealed its stake had risen to 42.6% - saying it had chosen to make the announcement because of uncertainty in the car market.
It had previously already been been the largest shareholder, holding about 35%.
Porsche has said it did not want to merge with VW - but create an alliance that could take on competition.
It has also argued that it needs a strong influence at VW, which makes components for a third of Porsche cars.
The car industry, which is often seen as a barometer of the world economy, is entering a deep recession, with sales and profits tumbling.
Manufacturing plants are closing, production is being cut back, jobs are being axed and car company share prices are tumbling as a consequence.
Last week Porsche said disagreements between family members in the company had been resolved.
Two cousins, Wolfgang Porsche and Ferdinand Piech, have held conflicting opinions on how to take over VW.
Mr Piech - who is both the Porsche boss and head of the VW supervisory board - has backed unions who object to the takeover of their company.
But Mr Porsche said that the families were "united" on plans including the idea of co-management of both companies.
The so-called "VW Law" - which essentially gives German authorities the right to veto strategic decisions Volkswagen - will also be scrapped.