Bayer AG has acquired a majority stake in birth control maker Conceptus Inc. and expects its $1.1 billion purchase of the California company to be completed soon.

Bayer said Wednesday that more than 96 percent of the company’s outstanding shares were validly tendered and not withdrawn during an offer period that expired Tuesday. That amounts to nearly 32 million shares.

Each outstanding share of Conceptus stock will be canceled and converted into a right to receive $31 per share in cash.

Conceptus, based in Mountain View, Calif., makes Essure, an irreversible birth-control method in which small metal and polyester coils are inserted to block a woman’s fallopian tubes. The procedure can be done in 10 minutes in a doctor’s office. Bayer already markets birth control pills and intrauterine devices.

Bayer announced its plan to acquire Conceptus in April and then said last month it received antitrust clearance from the Federal Trade Commission