Takeda has completed the takeover of London-listed Shire ahead of schedule after shareholders overwhelmingly backed the controversial $59bn (£46bn) deal last month.
The acquisition, which becomes the largest ever for a Japanese company, won 89 per cent approval in December despite a battle over the future of the company.
It creates a $30bn pharmaceutical giant primarily focused on oncology, gastroenterology, neuroscience, rare diseases and plasma-derived therapies.
It propels the 237-year-old Japanese drugmaker into the big-league, making it one of the world’s ten biggest pharmaceutical companies.
Chief executive Christophe Weber, who faced down pressure from influential shareholders to push the deal through, said the he is pleased to finalise the takeover months earlier than initially expected.
“This marks a significant moment in Takeda’s history and is an exciting step forward as we accelerate our transformation journey to deliver highly-innovative medicines to patients around the world with expanded scale and geographical footprint,” Weber said.
“The execution of our integration begins today, and we are confident in our ability to execute a smooth integration under the leadership of our experienced and diverse Takeda executive team with a strong track record.”
Several shareholders, including descendants of founder Chobei Takeda, had publicly voiced their concerns over the deal, fearing it would change the company’s culture and plunge it into nearly $31bn of debt.
Shares have dropped around 20 per cent since the deal was first acknowledged in April, while rating agency Moody's has downgraded the drugmaker.
Takeda today said it was “confident that it will retain its investment-grade credit rating”.