The market trends reported in newspaper groups Johnston Press and Trinity Mirror's trading statements today were nearly identical, but while Trinity shares gained slightly amid a general market decline, Johnston's slumped more than 37%.Johnston, publisher of the Scotsman, the Yorkshire Post and a host of smaller titles said advertising sales during the 19 weeks were down by 34.4% compared with the same period the previous year. Similarly, Trinity Mirror, publisher of the Mirror and many local titles, said revenue in the first 17 weeks of 2009 fell by 18% with advertising down by 30%.However, it was Johnston Press's balance sheet rather than current trading that had alarm bells ringing today.Net debt is down by £29m from the start of the year at £448m, but Johnston said that it has given up trying to sell its Irish titles after failing to receive any offers to its liking.This has resulted in a strong likelihood of a breach of a financial covenant in the group's debt facilities during 2009, the firm said, adding that it had begun discussions with its debt providers to obtain a relaxation in debt covenants.Shares in Johnston Press have soared since the company in March raised concerns over whether it can survive the current downturn as a going concern.They're still more than double what they cost a month ago, but today's update and the subsequent share price slide suggests those concerns may still be apposite.