Bill Gross Leaves Pimco, the Company He Founded, for Janus Capital

Pimco wouldn't have existed without Bill Gross. Now, it will live on without him.

In a shocking move, Gross has left Pimco, the company he founded in 1971, to join Janus Capital Group and manage its relatively new Janus Global Unconstrained Bond Fund. His employment begins Monday.

"Bill Gross has an exemplary track record with decades of success and he will offer an exceptional approach to navigating today's increasingly risky markets with a focus on macro, unconstrained strategies," said Janus CEO Dick Weil, a former Pimco executive who has an amiable and long-standing relationship with Gross.

Gross, 70, acknowledges that working with Weil was part of what motivated him to join Janus, along with the desire to abandon the complications of a larger organization. Janus Capital has $177.7 billion in assets under management while Pimco has $2 trillion.

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In his own statement, published by Business Insider, Gross said: "After having spent considerable time serving in senior management, it is a time for me to reduce executive and people management responsibilities at a larger firm and focus on the pure aspects of portfolio management at a smaller one. Janus is the right fit at the right time in my career — and my life."

Executives at Pimco may have wanted him to move on as well. According to CNBC's David Farber, "there was a good deal of tumult at Pimco in recent weeks" due to Gross's "increasingly erratic behavior." Insiders indicate that Gross would have been asked for his resignation as early as tomorrow. Moreover, the Securities and Exchange Commission was reportedly investigating Pimco's Total Return ETF, headed by Gross, to determine if the company inflated the value of assets after purchase.

Pimco is expected to name Gross's replacement later today. Dan Ivascyn, Pimco's deputy chief investment officer, is reportedly on the short-list for the position.