Bill Gross leaves PIMCO to join rival Janus Capital

Bill Gross, the head of PIMCO and known as the 'king of bonds' (Rex Features)

Bill Gross, the legendary manager and co-founder of PIMCO, has announced he is leaving the fund to join rival Janus Capital.

The announcement prompted speculation about the reasons behind the move after PIMCO issued a statement thanking him for his contribution, but noted that "over the course of year" it became "increasingly clear" that the firm and Gross had "fundamental differences".

His departure follows that of former chief executive Mohamed El-Erian, who left the firm in January, amid speculation that the pair had fallen out.

At the time, El-Erian, who was seen as his successor, said the two had "different styles of management", but insisted he left the firm to spend more time with his family. Speaking to Reuters earlier this week, he declined to discuss his relationship with the 70-year old.

The bond market took a hit in 2013 as investors switched money into shares from bonds, and PIMCO, which manages assets of roughly $2 trillion, suffered big outflows of money.

Gross will join Janus at the end of the month and manage the company's recently launched Unconstrained Bond Fund. He starts at the company on Monday.