Bond investment funds that usually have little appetite for riskier debt are boosting their exposure to the developing world, a move that is helping drive this year’s emerging markets rally.

International bond funds run by BlackRock, Legg Mason and OppenheimerFunds are among the big money managers that have been increasing their positions in emerging market debt in recent months. That shift reflects how global bond funds are feeling the pinch from low US interest rates and negative rates in Japan and much of Europe.