Bill Gross, the one-time bond king who built investing giant Pimco from the ground up 48 years ago then went on to run his own fund at Janus Henderson, announced his retirement Monday.

The retirement, effective March 1, marks the end of an era, closing a career for a fixed income expert who once had the ear of policymakers in the highest places. After leaving Pimco, Gross was never able to regain the standing he once held, and the fund he ran for Janus Henderson had badly underperformed for most of the nearly five years he had been there.

"I've had a wonderful ride for over 40 years in my career — trying at all times to put client interests first while inventing and reinventing active bond management along the way," the 74-year-old Gross said in a statement.

While at Pimco, Gross helped run the world's largest mutual fund, the Pimco Total Return Fund, which once boasted nearly $300 billion in assets. The fund began to hemorrhage investor money amid a battle at the firm's top between Gross and his co-CEO Mohamed El-Erian. Most recently, it was down to $65.6 billion in assets but has been outperforming its benchmark for the past three years.

Despite some well-chronicled acrimony between the two, El-Erian was complimentary of Gross on his retirement.

"Bill leaves behind him a long history of fixed income innovation, as well as investment approaches and frameworks that many investors still use today," El-Erian said in an emailed statement.

As for Gross' fund post-Pimco, the Janus Henderson Global Unconstrained Fund, its assets have contracted to $950.4 million — less than the $1 billion or so Gross had invested to start it. Over the past year, the fund is down 4.9 percent, near the bottom of its class, according to Morningstar.

In his farewell statement, Gross thanked "all of my past clients for their trust and support. I learned early on that without a client, there can be no franchise. I'm off — leaving this port for another destination with high hopes, sunny skies and smooth seas!"