Promethean World Plc, which makes electronic equipment for classrooms, declined by the most since its initial public offering in London trading after saying full-year results will miss estimates.
Promethean declined as much as 32 percent to 53 pence, the steepest drop since March, and traded at 55 pence at 1:07 p.m.
Fourth-quarter revenue will be lower than a year earlier, as governments and local authorities, particularly in the U.S., defer education spending, Promethean said today in a statement.
Analysts estimate full-year earnings before interest, taxes, depreciation and amortisation of 40.4 million pounds ($62.8 million) on sales of 249.4 million pounds, according to a Bloomberg survey.
Promethean, chaired by Orange co-founder Graham Howe, first sold shares to the public at 200 pence in March. Its previous owners included private-equity firm Apax Partners.