The move is part of a planned capital reorganisation following the group's review of its business and the disposal of certain titles, such as Racing Post, which it sold to Stradbrook Acquisitions in October as part of a £170m deal.
In order to secure clearance from the Pensions Regulator, Trinity Mirror will pay £108m into the group's benefit pension schemes, a move that shows it is "committed to funding the remaining deficits in its defined benefit pension schemes over time", it said.
The £175m share buy-back is more than £30m higher than the net proceeds from the disposal of its Sports division and seven sub-regions in the south following the deduction of the pensions contribution.
Trinity Mirror said the return of capital "would provide continuing financial flexibility for investment to create shareholder value".
Shares in the group were valued at 337.75p, down 0.59% from an opening 339.50p.
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