Grainger joined the firm in 2015 to lead the fixed income and currency portfolio management team. In his 25 years in the industry, he also held roles at Wellington Management, F&C Asset Management, Gartmore and Barclays Global Investors.
His exit follows the rebranding of Schroders' global fixed income and currency desk to the global unconstrained fixed income team, led by Julien Houdain, who was promoted to the newly created role of head of global unconstrained fixed income earlier this year.
A spokesperson said: "Paul is on gardening leave having left the business with our thanks and best wishes."
Schroders renames global fixed income desk and reshuffles manager lineup
As part of the reorganisation of the team, there were also changes to the manager line up of Schroders' fixed income funds.
Grainger managed the £111m Schroder Gilt and Fixed Interest fund since 2016, but had now been replaced by Houdain, who will run the strategy alongside James Ringer.
Houdain also took over management of the £592m Schroder Sterling Broad Market Bond fund and £66.1m Schroder Sustainable Bond portfolio.
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Martin Coucke, co-manager of the $2.9bn Schroder ISF Global Credit Income fund, joined the management of the £192.5m Schroder Strategic Bond fund, currently run by Houdain and Daniel Pearson.
Ringer and Robbie Boukhoufane are currently listed as the co-managers of the Schroder Sustainable Bond fund, however, Boukhoufane left Schroders in July, according to his LinkedIn profile.
The global unconstrained fixed income team now manages over $48bn of assets, with 20 investment professionals within its global fixed income platform.