Shares in Irish chip designer Parthus fell almost 10 per cent to 51p in London this morning after a downgrade from London investment house UBS Warburg.
Warburg cut its target price on Parthus to 45p from 120p and repeated its guarded "hold" ratings on the stock.
Elsewhere, shares in troubled telecoms equipment maker Marconi have sunk to fresh lows after rival Nortel Networks reported overnight a stinging second-quarter loss and a plunge in sales.
Nortel reported its optical components division saw a 78 per cent decrease in second-quarter sales on a year ago, with intercity optical sales experiencing the brunt of the decline.
The downbeat mood was intensified by comments from Swedish telecoms equipment maker Ericsson today. Reporting a second-quarter loss in line with expectations, it said market uncertainty had worsened and made a forecast for the full year impossible.
Marconi's share price fall extended this week's journey into the red, having already flopped 50 per cent this month after a profits warning. By 11.27 a.m. the stock was trading at 93.5p, down 4.1 per cent, having briefly hit the 92p level.
Marconi's decline was helped by worries over delays in the roll-out of third-generation (3G) Internet-enabled cellphone services. Earlier Vodafone said the rollout of 3G could slip to 2003 due to a potential shortage of handsets.
Additional reporting by