PIMCO’s chief investment officer and co-founder William Gross, whose views often move markets, is leaving the firm to join Janus Capital Group.

PIMCO has named Daniel Ivascyn as its chief investment officer, replacing bond heavyweight William Gross, who is leaving the firm he co-founded over 30 years ago to join rival Janus Capital Group. PIMCO has also made a number of other senior changes.

The news comes after the announcement that a fund run by market-moving commentator Gross has come under investigation over allegations that managers inflated returns and also a spell of poor performance for PIMCO’s flagship Total Return fund.

Gross starts at Janus in Newport Beach, California, today and will manage the recently launched Janus Global Unconstrained Bond fund. He will be responsible for building-out the firm’s efforts in global macro fixed income strategies, Janus Capital said.

Meanwhile, PIMCO also named Andrew Balls, Mark Kiesel, Virginie Maisonneuve, Scott Mather and Mihir Worah as chief investment officers. Kiesel, Mather and Worah will also be the portfolio managers for the firm's Total Return fund. Douglas Hodge and Jay Jacobs will continue in their roles as chief executive officer and president, respectively.

“While we are grateful for everything Bill contributed to building our firm and delivering value to PIMCO’s clients, over the course of this year it became increasingly clear that the firm’s leadership and Bill have fundamental differences about how to take PIMCO forward,” said Hodge.

According to The Wall Street Journal, the Securities and Exchange Commission is investigating whether the Pimco Total Return exchange traded fund artificially inflated its returns.

Victoria Hasler, senior investment research analyst at investment company Square Mile, said Square Mile would not be changing its ratings on the Allianz Gilt Yield fund and the PIMCO Select UK Income as a result of the news.

“Whilst the funds use the PIMCO process, and in particular the output from the secular investment forum chaired by Mr Gross, both funds are UK focused and managed using the experience and expertise of the European investment team. It should also be noted that PIMCO has, over the years, attracted the highest calibre of investment professionals and we have no reason to doubt that the debate, discussion and output from PIMCO’s investment team will suffer as a result of Mr Gross’s departure," said Hasler.

“At this juncture, we have every confidence in Mike Amey’s continued ability to manage these funds to a very high standard and to meet his investment objectives. We reiterate our A rating on the Allianz Gilt Yield fund and our AA rating on the PIMCO Select UK Income fund, though we shall continue to monitor developments with interest,” she added.

PIMCO has seen a number of high level moves in recent months, including the departure of former chief executive officer Mohamed El-Erian, who is said, according to reports, to have left following disagreements with Gross. In addition to naming Douglas Hodge as replacement CEO, PIMCO also appointed six new deputy investment chiefs as part of a management restructure.

PIMCO was founded in 1971 and bought by German insurance and financial services giant Allianz in 2000. In May, Frankfurt-listed Allianz reported a fall in operating profit at its asset management arm of 26 per cent, driven largely by net outflows of €21.7 billion ($29.7 billion) from PIMCO.