Bill Gross' Pimco Total Return Fund, the world's largest bond fund, posted $4.5 billion in net outflows for June, its 14th straight month of investor withdrawals despite an improving performance, Morningstar data showed on Wednesday.

The fund has had $64.1 billion in outflows since May 2013, the data showed. It had $225 billion in assets at the end of last month, down from a peak of $292.9 billion in April 2013.

The record outflow streak continued despite the fund's 0.37 percent gain in June, which beat 88 percent of peers, according to Morningstar. That said, the fund is up 3.70 percent for the year and is trailing 71 percent of its peers.

Analysts have said that outflows began last year on weak performance, which led the fund to decline 1.9 percent for 2013 in its worst performance in nearly two decades. Manager Gross' public falling-out with former heir-apparent Mohamed El-Erian, who shared the co-chief investment officer title, also exacerbated investors' unease.

A Pimco spokesman said in a statement: "Patient investors are rewarded over the long term by sticking with core bond allocations in a diversified portfolio. The Pimco Total Return fund has outperformed its benchmark and a majority of its peers over the last 1, 3, 5, 10 and 15 years."

The Pimco Total Return Exchange-Traded Fund, an actively managed ETF designed to mimic the strategy of the flagship mutual fund, had net inflows of $33 million in June, breaking its outflow streak, according to Morningstar. Total assets in the fund at the end of June were $3.4 billion.

Over more than three decades, Gross has become known as the market's "bond king" because he made so much money for clients that he has become the barometer by which other bond traders are judged. His West Coast perch, prescient calls on the U.S. economy and devotion to yoga only added to the mystique.

Gross, co-founder of Newport Beach, California-based Pimco, reiterated in his latest Investment Outlook report Wednesday that he favored credit and stocks as well as selling volatility "although we would acknowledge, as I have, that the alpha heyday of all risk premiums is over."

Pimco, a unit of European financial services company Allianz SE, had $1.94 trillion in assets as of March 31, according to the firm's website.