Bill Gross's exit from the investment firm Pimco had an immediate impact on the company, with investors withdrawing about $10 billion following the announcement, the Wall Street Journalreported, citing a person familiar with the matter.

Withdrawals were widely expected after the exit of Gross, one of the company's co-founders, who announced his department on Friday. Gross had managed the $222 billion Pimco Total Return Fund, the world's largest bond fund.

On Friday, Morningstar analyst Vincent Lui estimated that Gross's departure could lead investors to pull hundreds of billions of dollars in assets from Pimco and invest them with Janus Capital Group, the firm Gross joined.

Investors have already pulled almost $70 billion from Gross's flagship mutual fund from May 2013 through August 2014, according to Morningstar data, reducing the fund's assets from a peak of $292.9 billion in April 2013.