Proteus's shares tumbled 31p to close at 394p, the company's second large fall this year. Last week the market reacted coolly to the announcement of an interim pre-tax loss, marking the shares 19p lower.
The departure of UBS came only four months after its appointment by Proteus. The house was understood to have been selected from a shortlist because of its perceived ability to place shares later this year when further cash is expected to be required. Proteus retains Allied Provincial as its sole broker.
Kevin Gilmore, chairman, said UBS was new to the sector and had not properly understood new fast-track drug development systems, which saved time by overlapping stages of the testing process.
But he added: 'There has been no row. This was a genuine difference of opinion.'
Floated in 1989 at 87p, the shares have soared on hopes for the company's unique computer-aided molecular design systems. It is yet to make any profits and is spending about pounds 5m a year on development.
The company recently formed joint ventures with Medeva and American Home Products.
Proteus hopes to have 10 human and animal products in the first stage of clinical trials by the end of the year. However, it will be at least five years before any of its products for humans have passed through all the regulatory hoops.Reuse content