Dealings in the company's paper were suspended nine months ago after it ran into serious financial problems caused by the recession and the high costs of an acquisition spree.
A complex refinancing at 20p a share earlier this month has enabled it to return to the market. However, the rescue, involving a near-doubling of its share capital, has diluted shareholders' interests.
Mosaic was formed in 1987, when Greg Hutchings, who built up Tomkins from a small engineering company to one of Britain's biggest groups, took a controlling stake. His plan was to use Mosaic as an investment vehicle for acquiring businesses that were too small for Tomkins. One of its ventures included merchandising of cartoon characters such as Dennis the Menace, and UK rights for Teenage Mutant Ninja Turtles.
But the dream turned sour after Mosaic ran up a huge bill in deferred payments.
As part of its rescue, Mr Hutchings has resigned from the board. His stake in the company has been diluted by half to 4.3 per cent.
Yesterday's fall in the shares was in line with expectations. Last month the company reported interim pre-tax profits of pounds 207,000 for the period to last October, compared with profits of pounds 3.2m in 1991.