Brussels court rules in favour of Fortis small shareholders
It also put a 65-day freeze on government involvement in the bank and insurance group.
Hard hit by the global financial crisis, Fortis was dismantled in October, with its Dutch assets nationalised by the Netherlands for 16.8 billion euros (22 billion dollars) and its Belgian and Luxembourg activities sold to French bank BNP Paribas.
In its ruling, the court said decisions taken by Fortis - ranked by Fortune magazine in 2007 as the world's 20th biggest company in terms of revenue - on October 3, 5 and 6 had to be approved by shareholders.
It also put a 65-day freeze on government involvement in the bank and insurance group, and ordered the appointment of a panel of two "wise men" and three technical experts to review the transactions.
During the same period, BNP Paribas is to maintain normal inter-bank relations with Fortis, the court of appeal added in a 141-page ruling, the first 93 pages of which bore the names of 493 plaintiffs.
"It's a victory right across the board," said Olivier Bonhivers, one of the shareholders' lawyers, quoted by Belga. "The courage and independence of the judges of the court of appeal in Brussels must be saluted.
October 3 was the day Fortis, on the brink of bankruptcy, decided to hive off its Dutch assets to the Netherlands government. Two days later, BNP Paribas announced it was taking over the Belgian and Luxembourg operations.
The European Commission, which enforces EU anti-trust laws, approved the BNP Paribas side of the break-up on December 3, saying: "The transaction would not significantly impede effective competition."
But in a separate case, Dutch shareholders have gone to court to seek relief against executives they accuse of keeping quiet as the bank bled 44 billion euros in 18 months.
Belgian authorities are meanwhile investigating whether Fortis executives misled investors.
Closely involved in Fortis has been Ping An, China's second largest life insurer, which spent 1.8 billion euros to acquire a 4.18 percent stake last year -- one of the largest-ever overseas acquisitions by a Chinese insurer.
The stake was later raised to 4.99 percent, but Belgian Prime Minister Yves Leterme on December 1 rejected demands for Ping An to be compensated for its soured investment.