Bond investors in PIMCO’s Total Return Fund are being urged to remain loyal to the fund after Bill Gross’s departure after new analysis showed detriment to investments after leaving.

Data from Aegon, the Dutch insurance firm, showed nine from 11 funds still outperformed benchmarks even after the departure of a significant fund manager.

Aegon’s investment director, Nick Dixon, said investors in Gross’s former funds should “think carefully” before making any snap redemption decisions.

The analysis was done after Bill Gross stepped down as CIO at PIMCO, a company he started in 1971, and left to manage a new, much smaller bond fund at Janus Capital Management.

The shock departure led to the swift appointment of Daniel Ivascyn as the California-based manager looked to calm fears among investors and stem outflows from Gross’s former flagship fund.

PIMCO confirmed that its September net outflows from the $211bn (€167bn) Total Return Fund hit $23.5bn, with the largest daily outflow happening immediately after Gross’s resignation was made public.

However, the company also stressed that outflows on the following two days were significantly lower.

Aegon’s analysis showed other key-man departures had little impact on the institutional and retail funds they managed, with some new managers outperforming their predecessors.

It highlighted UK asset manager Schroders’ loss of Richard Buxton from its UK Alpha Plus fund, who left the firm after 11 years. Buxton’s replacement Philip Matthews still managed to achieve 2.8% above benchmark for the fund.

The manager’s European Opportunities fund, managed for 11 years by Chris Rice until 2013, saw replacement Steve Cordell achieve returns of 5.3% above benchmark, higher than Rice’s annualised return in his time in charge.

Other ‘key-man’ losses for Fidelity, Henderson and AXA Framlington also saw replacement managers stabilise the funds and achieve above-benchmark returns.

Dixon said investors considering exiting PIMCO’s previously coveted fund should strongly evaluate their decisions before moving assets.

“Bill Gross has left a distinct investment DNA at PIMCO, with talented analysts and a strong team culture,” Dixon said.

“These qualities will endure for many years after Gross’s departure and should be reflected in PIMCO’s future performance.

“It is also important to think hard about the costs associated with moving money – potential fees, out of market risk and missing likely gains from existing funds. Investors must weigh up the benefits with the costs and remember that often the wisest move may be to stay put.”

At PIMCO, Gross’s shock departure is only a continuation what has been a turbulent period for the bond house.

Earlier this year, then chief executive Mohammed El-Erian stepped down, raising questions about the expected succession plan for the 70-year-old Gross.

Since the start of the year, outflows from the Total Return Fund have been consistent, as investment performance began to slide on a short-term basis.

This was capped by the eventual departure of Gross, which sent shockwaves through PIMCO and its investors.

Gross will begin managing an unconstrained bond portfolio at Janus on Monday.

In an update to investors, PIMCO said: “As we engage our clients around the world, we are confident the vast majority of them will continue to stand with PIMCO as we demonstrate why we have earned the reputation as one of the world’s premier investment managers.”