The group is now set to bank £450 million from offloading papers including the Racing Post – around a quarter less than expected.
The news from the Daily Mirror publisher sent shares tumbling 6 per cent and overshadowed better-than-forecast interim profits.
Trinity Mirror posted first-half underlying pre-tax profits of £98.2 million, up 7 per cent on the same period last year.
Adjusted group revenues fell by £1.9 million to £526.3 million, but the group said tight cost controls helped offset the fall.
Cost savings of £6 million were delivered in the six months to July 1, leaving the group on track with plans to trim £10 million in costs for the full year, leading to savings of £20 million next year.
But the results failed to appease shareholders left disappointed by the revised disposals proceeds.
Trinity Mirror has so far raised £92.9 million from the sale of titles across London and the South East, including a deal yesterday to hand 27 papers to Tindle Newspapers for £18.75 million.
The group is yet to sell its flagship sports title, Racing Post, and a number of remaining regionals, including the Birmingham Post.
It had been reported that Trinity was in talks with a group of Irish investors over a possible deal worth £190 million for the Racing Post, but no update was given, except confirmation that all disposals are due to be completed by the end of the third quarter.
Trinity reported a 29% rise in operating profits to £8.9 million for its sports titles.