US - Pension funds in the US and other institutional investors are losing billions by changing investment managers at the wrong time, research from Boston University has shown.
He said: "They think its clean slate but what they don't realise is the performance of that manager tends to reverse.
"Each pension plan needs to go through and not just look at the managers they have hired, but look at the managers they have fired and evaluate whether their process is hurting them."
Stewart said there was a tendency among investors to chase performance and a lack of understanding on the difference between a deep value manager and a relative value manager.
He said: "Ten years ago, investors needed to understand the style of a manager, but what our research suggests is pension funds need to understand the extremeness of style.
"How much value does that value manager have? That is another source of misunderstanding."
Stewart recommended pension funds take care in chasing performance and instead look for opportunities rather than managers who have simply done well.
He said if a manager had performed poorly, the pension fund should ask if it was firing that manager at the wrong time.
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