UK drugs company AstraZeneca has rejected a final takeover offer from Pfizer.
The US company had made a new offer of £55 per share on Friday, valuing AstraZeneca at about £69 billion.
But AstraZeneca said on Monday the new proposal "undervalues the company and its attractive prospects".
Pfizer wants to create the largest drug company in the world, with its headquarters in New York, but based in Britain for tax purposes. AstraZeneca employs 6,700 people there.
Pfizer had said it would retain at least 20% in Britain for at least five years. It had also pledged to base its European HQ in Britain.
The BBC reports AstraZeneca shares fell by more than 13% after its rejection of the offer.
by our unprecedented commitments to the UK government."
Pfizer had said that its offer of £55 per share was "final" and would not be increased.