Roche Sinks as Family Cuts Voting Share Stake in Surprise (1)

Roche Holding AG’s shares dropped the most in nearly three years after the family that controls the Swiss pharmaceutical giant unexpectedly cut its stake.

An unidentified shareholder offered a 2.5% stake, which was quickly sold, dropping the Oeri-Hoffmann family’s control over Roche’s bearer shares to 65%. That stake is held in a group with pooled voting rights.

The shares were sold at 307 Swiss francs each, representing a 7.6% discount to the last close, and raised 828.9 million francs ($899 million), according to a person with knowledge of the matter.

The stock plunged as much as 7.9% in Zurich, ...