Fidelity Investments, a major investor in DuPont (DD.N), has put pressure on activist fund Trian Fund Management LP and the chemical conglomerate to reach a settlement in what it sees as a detrimental proxy fight, according to people close to the matter. Fidelity, whose 2.5 percent stake makes it DuPont’s sixth largest shareholder, has not publicly revealed what sort of compromise it was seeking. Yet its unusual intervention as peacemaker could influence other mutual fund investors in DuPont and pre-empt what could be this year’s biggest battle over board representation.