Japan's Softbank Group Corp. is in advanced talks to buy a stake in Swiss reinsurer Swiss Re AG worth $10 billion or more, the Wall Street Journal reported on Wednesday, citing people familiar with the matter.

Softbank is looking to purchase up to a third of Swiss Re's shares at a premium, the Journal reported.

The talks still could fall apart and there might not be a deal, the newspaper said.

The companies were not immediately available for comment.

The reinsurer's shares closed at 90.18 Swiss francs on Wednesday.