But the sheer size of the deal elicited resistance.
A group of shareholders led by Kazuhisa Takeda, a descendant of the founding family and a former board director,
and Shigeru Mishima, a former stockmarket analyst, was bitterly disappointed by this week's approval.
On the question of why the group opposed the acquisition, Mr Mishima cites "risk, risk, risk!".
Local rivals, Astellas and Daiichi Sankyo, which have chosen to make smaller acquisitions, of American biotechnology companies,
have seen their shares rise by 18% and 43% respectively, as Takeda's have fallen.
The dissidents may have a point. Scope for cost-cutting is relatively limited.
It will saddle the combined entity with $48bn of net debt, or over five times its expected annual operating earnings.
To bring the huge cost of servicing this down, Mr Weber will have to dispose of promising products worth $5bn after the firms merge, on January 8th.
He claims strong combined cash-flow will help pay down debt quickly,
but Shire's haemophilia drugs, worth a quarter of its revenues in 2017, are threatened by new drugs from other big pharma firms.
Mr Takeda and other dissident shareholders do not deny the company needs to diversify its range of products.
Nor, they claim, are they against acquisitions or globalisation. But the dose makes the poison. Swallowing Shire could prove toxic.