
Commercial's share has increased from 43.2% in the second quarter this year to 43.4% in the third quarter (28 June to 19 September), up year-on-year from 42.4%.
The BBC's share edged down from 54.6% in the second quarter to 54.3% in the third quarter, and is down year on year from 55%.
Having set a record with a reach figure of 32.87 million people last quarter, the commercial sector went beyond it to 33.37 million. It was the fifth consecutive quarter of growth, according to commercial radio trade body RadioCentre.
Amanda Burningham, ideation director at Interpublic media agency UM London, said: "It's really positive and encouraging to see continued growth in the medium. Often, there has been a yo-yo between commercial radio having a good Rajar, and then a bad one, but now its feels like consistent growth. All the radio groups have done well."
Andrew Harrison, chief executive of RadioCentre, said: "This is another very encouraging set of results for the commercial radio sector. On reach this is our second consecutive quarterly record, with listener hours also up modestly quarter on quarter.
"The fact that commercial radio continues to grow listeners and gain market share against the backdrop of relentless competition for listeners’ time is a reflection of the sector’s ongoing momentum."
According to one view from the City, radio's continued popularity and improved advertising performance will not stop the process of consolidation in the industry.
Sean Duffy, head of technology, media and telecoms at Barclays Corporate, said the figures affirmed radio's resilience and media buyers were looking to spend.
But he added: "Spending cuts affecting the Government’s Central Office of Information (COI), from which many stations derive a substantial proportion of their income, will see previously guaranteed revenue streams diminish in the near future, particularly for national stations.
"With little room left to strip out costs from most stations, this will again put consolidation pressure on the industry, and we are likely to see more standalone and regional operators snapped up by larger players."