Swiss financier Martin Ebner's debt-laden BZ Group is to sell its 19.8 per cent stake in life sciences group, Lonza.
The Ems-Chemie group, owned by Ebner ally Christoph Blocher, has increased its shares in Lonza from eleven per cent to 20 per cent.
Ems-Chemie made the announcement after the bourse closed on Friday. It has not yet been announced whether the shares were bought from Ebner.
Lonza also said on Friday that Ebner would also be stepping down as chairman with immediate effect.
The sale of the Lonza stake is the latest attempt by Ebner to shore up his company's battered finances after they took a hammering on the financial markets.
Lonza said in a statement that the much-expected sale of the stake - worth SFr850 million ($576.7 million) - would take place within the next few weeks.
Fears of sales by Ebner have weighed on the stock market and Swiss firms in which his BZ Group has shares, such as the engineering group ABB, the bank Credit Suisse and the insurer Baloise.
The sale of Ebner's stake follows on from a tough year for the BZ Group.
In July, it was forced to sell off its controlling shares in four listed investment funds, which had equity holdings worth SFr3 billion, to Zurich Cantonal Bank.
Then in August, Credit Suisse, German and Austrian banks granted Ebner relief on an estimated SFr3 billion in loans so that he could stabilize his BZ Group.
In a statement, Lonza said that its board had been informed by the BZ Group of its intention to sell its 19.8 per cent interest in the group
Lonza added that Ebner's position as chairman of the board of directors of Lonza would be filled by Sergio Marchionne, formerly vice-chairman of the board.
Lonza declined to comment on whether a buyer had been identified, saying that management would be prepared to go over the books with any potential "buyer or buyers".
Market speculation had centered on Blocher, who is head of EMS Chemie and already owns 11.2 per cent of Lonza.
Before Ems-Chemie's statement on Friday, Blocher had told Reuters that he did not rule out increasing his stake if needed or if it was in Lonza's interests.
The 56-year-old Ebner built up his BZ Group after leaving a career in investment banking.
The multi-millionaire - who styled himself on the American investment tycoon, Warren Buffet - convinced thousands of Swiss to sink money in his investment accounts rather than in lackluster savings accounts.
But his liquidity position was badly hurt this year when a flood of retail investors sought to bail out of the stock market, forcing the BZ Group to fork out hundreds of millions of francs.
swissinfo with agencies
The BZ Group is run by flamboyant Swiss financier, Martin Ebner, who championed the small investor until his company fell foul of the financial markets.
The group is to sell 19.8% share in Lonza worth SFr850 million.
In July, Ebner sold shares in four listed holdings to shore up its finances.
In August, the BZ Group was granted SFr3 billion debt relief by banks.