National and regional newspaper publisher Trinity Mirror's share price has continued to sink today - down around 20% in early trading - over market fears it will have to plough more funds into its sizeable pension scheme.

The publisher of the Daily Mirror, Sunday Mirror and Liverpool Post saw its share price fall to 43.75p at 9.45am, down 11p on the closing price yesterday.

This followed a share price fall of 12.5p, around 18.6%, in trading yesterday.

The share price tumble yesterday is thought to have been triggered in part by an analyst note from investment bank Kaupthing.

The note questioned Trinity Mirror's pension fund situation and argued that another 5% fall in ad revenue in 2009 could mean that the publisher could breach the covenants of a new five-year bank loan of £210m.

"The market is concerned about Trinity Mirror's pension fund. The issue is not that there is a huge deficit at the moment, just that it is a very big scheme," said one City analyst.

Trinity Mirror's share price plunge in recent weeks has seen the publisher's market capitalisation fall to £141m.

The City is concerned that if the pension scheme, which has gross liabilities of around £1.5bn, requires topping up, Trinity Mirror may struggle to raise funds.

"There is currently a small deficit but with a weakening stock market performance there are concerns that that Trinity Mirror may require more money to go into the scheme," said the analyst. "With a small market capitalisation and a tough economic outlook there are concerns about raising funds."

Trinity Mirror has experienced a torrid two weeks since it issued a trading update on Monday June 30 forecasting a 10% decline in full-year operating profit.

Shares in the company had closed at 151.5p on Friday June 27, but over the next three days slid to just 90p.

Its profit warning triggered a knock-on effect among media companies reliant on advertising revenues, particularly those with exposure to regional publishing, which saw major share price falls at Johnston Press, Daily Mail & General Trust and ITV.

Trinity Mirror declined to comment.

ITV's share price rose by 12% to almost 43p on Monday after rumours that the broadcaster might be the target of a takeover. The company's shares were trading at around 40p at 10.44am today.

Daily Mail & General Trust's shares were down 2.5p, around 1%, to 259p at 10.48am.

DMGT, which owns the Daily Mail, saw its shares fall by 13.5p yesterday, just under 5%, in reaction to Trinity Mirror's slide.

Johnston Press has seen its share price increase by 0.75p, around 2.13%, on its closing price yesterday to 36p at 10.55am today.

· To contact the MediaGuardian news desk email editor@mediatheguardian.com or phone 020 7239 9857. For all other inquiries please call the main Guardian switchboard on 020 7278 2332.

· If you are writing a comment for publication, please mark clearly "for publication".