Shares in Alterian have plunged by almost 35% after the marketing software company issued its second profits warning in little more than a week.
The firm said revenue for the last financial year would be "materially lower" than its forecast last Monday of a 10% shortfall in market expectations.
Last week's profit warning led to the resignation of the firm's chief executive David Eldridge.
The company said it would make a further statement on 18 April.
Alterian's customers include carmaker Jaguar Land Rover, Domino's Pizza and pharmaceuticals giant AstraZeneca.
Shares in London fell 57.5p, or 34.7%, to close at 108p.