GCap Media, the UK's biggest commercial radio broadcaster, has announced that its chief executive Ralph Bernard is stepping down.
Mr Bernard has been head of GCap and GWR, which merged with Capital Radio to form GCap, for the last 25 years.
GCap, hit in recent years by falling advertising revenues, reported a 3% fall in six month underlying pre-tax profits to £5.6m.
GCap's stations include Classic FM, Capital and several digital channels.
"This is the right time to step down as chief executive," Mr Bernard said.
"This is a pivotal time for the industry, further consolidation is likely," he added.
Mr Bernard will stay on until a successor can be found.