Shares of Takeda Pharmaceutical opened lower on Friday, down 3.7 per cent (Y5,210), after the Osaka-based company announced it was buying Millennium Pharmaceuticals, a US biotechnology company with an approved cancer drug, for $8.8bn in cash, in the biggest foreign acquisition by a Japanese pharmaceutical company.

Takeda will launch a tender offer of $25.00 a share, a premium of 53 per cent on Millennium’s Wednesday closing price of $16.35. Millennium, whose board unanimously approved the offer, said it would become a wholly owned subsidiary of the Japanese company but that it would continue to operate as a standalone business unit in Boston.