Bill Gross' decision to depart as Pimco's chief investment officer to join Janus Capital Group shocked most of the financial community.

That includes Vanguard Group founder Jack Bogle. "I don't shock easily, but I was surely shocked when I heard that basically as soon as I got in the office at about 8:30 this morning," he told CNBC. "I think it's too bad. It's too bad for Pimco."

Gross has been under fire since Mohamed El-Erian quit as Pimco's CEO earlier this year — reportedly because of disputes with Gross — and returns in Gross' signature mutual fund, Pimco Total Return, sagged.

For the last year, the fund ranks in the 79th among its peer intermediate-term bond funds, according to Morningstar.

In addition, the Securities and Exchange Commission is investigating whether Pimco's Total Return ETF bought bonds at discounts and then marked them up, a knowledgeable source told Bloomberg.

Gross was about to be fired from Pimco due to increasingly erratic behavior, according to CNBC.

"Maybe all the politics that came to be involved in the management of Pimco, the SEC challenging the pricing of some of his bonds [and] all those little fits probably just drove him up the wall, and he said, 'Who needs this?'" Bogle noted.

As for Pimco, "this raises a real question mark about the stability of the entire organization," Burton Greenwald, a Philadelphia mutual-fund consultant, told Bloomberg.

"Until they show some positive developments, they will have a difficult time raising assets. Whatever momentum they had will be lost."

Related Stories:

• Bond King Bill Gross Leaves Pimco to Join Janus Capital
• Pimco Said to Be Likely to Pick Dan Ivascyn to Succeed Gross