As reported by Fairfax Media, the figures showed the pay TV ad market shrunk by 4.4 per cent - its first ever decline, albeit after a bumper prior corresponding period. Citi analyst Justin Diddams noted the ad-market decline was likely linked with pay TV's share of audience viewing declining through 2014.

Print advertising fell by 18 per cent over the first half of 2014, while online surged by 21 per cent, the Commercial Economic Advisory Service of Australia (CEASA) figures showed.

The metropolitan free-to-air television ad market grew by 1.2 per cent, while the regional market was off by 1.5 per cent. Overall TV ad spending was down 0.1 per cent year-on-year.

Diddams said the "key takeaway from the data is the continued robust growth of online/digital at the expense of print and a few other platforms".

He lowered his ad-market forecasts to 2.2 per cent, from 2.5 per cent, and tipped a larger 5 per cent year-on-year decline in traditional media advertising for the 2014 calendar year.

Diddams also noted that "regional has underperformed since the beginning of 2013, with both TV and radio market declining, and print is now following a similar path. The pullback in government spending in these markets has hammered growth."

Shares in publishers Fairfax Media - owner of The Age and Sydney Morning Herald - closed down 3.13 per cent on Wednesday to 77.5¢, and News Corp shares fell 2.45 per cent to $17.53.

TV companies Nine, Ten and Seven West Media each fell more than 1.5 per cent, about double the fall in the S&P/ASX 200. Ten, the lowest rating commercial network, closed down 2.27 per cent to 21.5¢, near its 2012 low.

For radio companies, APN News & Media ended up flat at 82¢ - having fallen more than 2 per cent during the day - while Southern Cross fell to a three-year low of 92.5¢, down 2.1 per cent.

Diddams said the emerging battle for revenue share between Southern Cross, APN and Lachlan Murdoch's Nova "represents a potential risk to revenue growth in the sector", and has forecast no growth in metro radio for the next two years.

But figures from industry body Commercial Radio Australia showed that radio revenue for Melbourne, Sydney, Brisbane, Adelaide and Perth was 9.2 per cent stronger in September, at $63 million.

The figures were higher than expected, according to Goldman Sachs analyst Jacqueline Thai and Christian Guerra, and the strongest month since November 2010.

"Given the large uplift in September, the first quarter [of the 2015 financial year] is now up 2.2 per cent, versus our first half metro radio ad market forecast of -1 per cent," the pair wrote.

"We wait to see further indications of October/November trends as these are traditionally the biggest months of the year for ad spend.

"We believe the strong September for metro radio bodes well for the overall ad market, but we remain cognisant that metro radio has been outperforming the total ad market in recent months."

The results followed a 0.1 per cent fall in five-city revenue in July, and a 2.4 per cent fall in August. July and August 2013 were strong due to the federal election.