The shares, which were pumped up by the planned high-premium merger only to slump when the plug was pulled last week, added almost 3 per cent, up 109p at 4,004p.
Chris Beauchamp, market analyst at IG, said: “Jilted Shire came out with all guns blazing to prove that it is perfectly capable of carrying on life as an independent firm.”
But rival AstraZeneca was down 7p to 4,327.5p after its US suitor Pfizer announced a share buyback programme – suggesting it is not mulling another takeover tilt for Astra.
The wider FTSE 100 was 30.42 points lower at 6,388.73 ahead of the expected publication this weekend of the European Central Bank’s stress tests on eurozone banks.
Tesco shares continued to fall as investors digest the collapse in its profits and uncertainty around the strategy of chief executive Dave Lewis.
Rating agencies Moody’s and Fitch both downgraded the firm’s debt after its last update, while traders are anxious about Tesco’s decision not to provide full-year profit guidance. Shares in Britain’s biggest supermarket fell by further 1 per cent, or 2.25p, to 168.75p, with rival Morrisons off 0.6p to 152.5p.
Travel stocks, which have been weighed down in recent weeks in the light of the Ebola threat, took a further hit on news the disease had reached New York, with EasyJet off 13p at 1,438p and British Airways owner IAG down 0.7p to 383.3p.
Elsewhere, Spirit Pub Company lifted 1p to 107.25p as it emerged that Magners maker C&C Group has tabled a bid proposal that could scupper Greene King’s existing £750 million takeover offer.