Previously, Milson was lead manager on the Higher Income Fund after joining SLI in 2006.
He will continue to work as back-up manager on the fund, but will have primary portfolio responsibilities within the group’s global high yield portfolios, working closely with the credit team in Boston.
Ennett, who joined SLI in March 2010 from Old Mutual Asset Managers, is also responsible for its Euro High Yield Sicav and the high yield elements of the Select Income and Strategic Bond funds in the group.
The SLI Higher Income Fund has underperformed its benchmark in the past three discrete years to 31 December and its cumulative performance is also lagging.
SLI said the change was the result of a regular review and reflected its "continued desire to ensure" it operates with maximum efficiency.
It added that over the past couple of years the Edinburgh-based high yield team had seen an increase in both assets and mandates under their management and in members and that with the development of a global credit offering the team was required to work closely with its Boston-based credit team.
A spokesperson for SLI, said: "Both managers [Milson and Ennett] will continue to operate in a dual role with their time shared between portfolio management and research responsibilities.
"The high yield team in Edinburgh (four members) continue to work closely with our high yield team in Boston (six members) and our wider credit team (20 members), applying our proven credit process and focus on change philosophy to add value for investors."
OBSR announced it had suspended the Higher Income Fund’s A rating due to the manager change and would meet the team in the coming weeks to discuss the implications of the switch.
