No official reason was given, but market sources suggested Northumbrian was about to sell a recently acquired company for a fraction of the price it paid.
Northumbrian is thought to be about to sell Lees, a Scottish producer of flapjacks, meringues and snowballs. It bought Lees for pounds 4.8m in September 1991.
However, in July 1992 - shortly after the departure of the former chief executive, Richard Adams - Northumbrian's chairman, Kevin O'Keefe, said he was unhappy about the terms of the Lees acquisition.
Northumbrian was to have published interim results on Wednesday, but postponed the announcement at short notice.
In the last published results, to March 1992, Northumbrian made pounds 154,000 compared with pounds 263,000, and passed the final dividend. BZW, the broker, was predicting that the company would only break even this year.