Pacific Investment Management Co's flagship fund dropped below $100 billion in assets for the first time in more than eight years, leaving it with about a third of the money it managed at its 2013 peak.

Investors pulled $1.8 billion in assets from the Pimco Total Return Fund in August, down from $2.5 billion the previous month, according to the Newport Beach, California-based firm on Wednesday.

After 28 consecutive months of outflows, assets plunged to $98.5 billion as of Aug. 31 from a peak of $293 billion in April 2013, when the mutual fund was the world's largest and run by Pimco co-founder Bill Gross.

Gross, the bond market's most renowned investor and long known as the "Bond King," shocked the investment world nearly a year ago when he quit Pimco for distant rival Janus Capital Group Inc.

This is the first time that Total Return assets had less than $100 billion since January 2007, before strong risk-adjusted returns during the financial crisis attracted monstrous inflows of cash from investors seeking the relative safety of bonds. Assets were $99.86 billion in January 2007, according to Morningstar data.

Investors have withdrawn record amounts of money since April 2013 because of erratic performance exacerbated by last year's departures by Gross and Mohamed El-Erian, the former chief executive officer of Pimco and Gross' heir apparent.

The Pimco Total Return Fund had cash withdrawals of $11.6 billion in January, though figures in recent months have reflected significant stabilization. Pimco Total Return has delivered returns of 0.72 percent so far this year, surpassing 85 percent of its category peers, Morningstar data show as of Aug. 31.

"We focus on investing client money using our time-tested strategy with the knowledge that it's risk-adjusted performance over the long term that ultimately matters to investors," said Scott Mather, lead manager of Pimco Total Return.

The Pimco Income Fund, overseen by Pimco Group Chief Investment Officer Dan Ivascyn who succeeded Gross, continues to see huge investor appetite, posting $9.5 billion in inflows since the start of the year, according to Pimco's website.

The fund had assets under management of nearly $50 billion as of the end of August, Pimco said.