Investors pulled a net $27.5 billion from Pacific Investment Management Co.'s flagship Total Return fund in October, the company said in a filing Tuesday, marking a mutual-fund industry record.

The amount represents the first full month of investor flow data since Bill Gross, Pimco's former chief investment officer and manager of the Total Return fund, left the company Sept. 26. Mr. Gross now runs a small mutual fund at rival Janus Capital Group Inc.

The Total Return fund's assets sunk to $170.9 billion, with most of the outflows happening in the first five trading days in October, according to the Pimco filing.

"Flows from the Total Return fund peaked on Sept. 26 and slowed sharply through October," the filing said.

A Pimco spokesman wasn't immediately available for comment.

Write to Kirsten Grind at kirsten.grind@wsj.com

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