The company, a favourite of private investors, became the subject of grief two weeks ago when it failed to clinch key deals with Johnson & Johnson, the US health giant.
In the summer the market grew restless about the proposed link and Bio's shares weakened. Doubts, however, were largely allayed by soothing comments from the company, which said negotiations continued and their scope had been widened.
Then the shock. Johnson decided to walk away from the main elements of the talks which covered the US group using Bio's special coating for stents - they hold arteries open during an operation - and marketing Bio's stents in the US.
The severe mauling accorded the once high-flying wonder share mainly reflects the fear Bio could have unwittingly unleashed a powerful rival - Johnson - in its narrow world of protective coatings. There is also dismay it failed to warn the market about the temperature of the talks.
And there is astonishment at the way Bio attempted to represent the reverse as progress. Chief executive Alistair Taylor actually said the setback was "great news" as it allows "us to distribute our own stents and look for another partner, perhaps one that is more aggressive".
Johnson, with 4.3 per cent of Bio, is still talking with the company about collaborating over an advance form of coating which would eliminate thrombosis. Still, Bio is not completely friendless. Merrill Lynch remains supportive and stockbroker Killik said the depressed price "totally undervalues" the group's technology.
Bio was not the only share under pressure. Blue chips had an off day although second and third liners achieved modest progress. Odd goings on in the futures market, a weak New York display and subdued government stocks after an uninspiring auction combined to unsettle equities.
Centrica led blue chips on continued Panmure Gordon support. The investment house sees the shares at 120p; they closed 2.5p higher at 90.25p.
Others higher included SmithKline Beecham, 4p (after 24.5p) at 558.5p following US approval for a Parkinson's disease treatment, and Burton, 3.25p better at 128.75p on Merrill Lynch support.
Lasmo, the oil group, rose 3p to 266.5p after reserve estimates were lifted for some of its Algerian fields. Three exploration concessions in Pakistan also fuelled the enthusiasm.
Properties were buoyant with British Land 10p harder at 615p. MEPC, regarded as a likely bid target, managed a 4p plus to 498.5p on its retreat from overseas and plans to hand pounds 300m to shareholders.
Another possible bid emerged in the hotel industry. Arcadian International, with a string of country hotels, jumped 15p to 65.5p after reporting an approach. Hanover International, which earlier admitted bid feelers, put on 4p to 147.5p.
Sentry Farming was the session's main casualty, falling 31.5p (after 42.5p) to 83.5p. It lost pounds 774,000 in its first half-year and suffered difficult a harvest which will produce lower year's figures.
Incepta, the marketing and PR agency, firmed to 20.5p. US investor Whitney Partners has sold its 5 per cent interest, mostly at 19.5p.
Brent International hardened to 79.5p. Vague takeover talk circulates. Martin Evans at stockbroker Sutherlands rates the shares a buy. "With historic sales of pounds 140m and a current market capitalisation of only pounds 53m, the valuation of the group is anomalously low, particularly with Brent on the cusp of sustained recovery." In the past year the shares have come down from 118p.
Pilkington was again heavily traded. The shares rose 4p to 155.5p with the warrants up 3p at 43p. The glassmaker has been the subject of intense market activity with Mercury Asset Management thought to have cut its stake.
Middlesex held at 8p. ABN Amro Hoare Govett has concluded it is "overlooked and undervalued".Reuse content