While stressing the board's confidence in the Anglo-Swedish firm's future as an independent company, chairman Leif Johansson has effectively laid out the conditions under which AstraZeneca would be prepared to negotiate. In a video message posted on the company's website, he said the board rejected Pfizer's approach because it "very significantly undervalued" AstraZeneca and its prospects. It also has concerns about the large proportion of Pfizer shares in the deal and the proposed tax structure of the combined company.