MORNINGSTAR: Hundreds Of Billions Of Dollars Could Follow Bill Gross

Shares of $2 billion Janus Capital exploded 42% and PIMCO parent Allianz fell by around 6% after it was announced that Bill Gross would be leaving PIMCO to manage a fund at Janus.

"We are placing no-moat Allianz under review while we assess the impact of the announcement," Morningstar's Vincent Lui wrote. "We expect to lower our fair value estimate, as it is likely that tens of billions, if not hundreds of billions in AUM, will follow Gross to Janus from Allianz."

As of June 30, PIMCO had $1.97 trillion in assets under management. Janus had about $177 billion.

"Tens of billions" and "hundreds of billions" is a pretty wide range.

Moves by big portfolio managers, however, are not unprecedented.

"We believe Jeffrey Gundlach's acrimonious departure from TCW in 2009 is a possible model, and we note that Gundlach's DoubleLine now manages more than $50 billion," Lui noted.

We'll keep in eye on the monthly fund flow stats.