Count Bill Gross among the world’s biggest philanthropists.

The bond investor has already given away as much as $700 million and eventually will donate his remaining $2 billion fortune, a figure that’s “staggering, even to me,” Gross said in an interview on Bloomberg Television.

“I define success differently now than five or ten years ago,” Gross said in the interview recorded April 29 at his office in Newport Beach, California. “Success in the early years was business-related, and asset growth-related, and of course, with family was related to how well your son or daughter was doing on the soccer field.” Today, “success becomes a function of what we can do with the rest of the world, to help others.”

Gross, 71, amassed his wealth as co-founder of Pacific Investment Management Co. and built his reputation as the “bond king” by generating years of industry-leading returns as manager of the Pimco Total Return Fund. In 2013, when the firm’s assets approached $2 trillion, Pimco paid him a bonus of $290 million.

The same year, hedge fund manager Carl Icahn, in a taunt on Twitter, challenged Gross to join other billionaires in leaving the bulk of his wealth to charity. Two days later, Gross said he and his wife, Sue, would give it all away.

Until now, Gross hadn’t discussed his total giving to date.

“Sue and I try and keep it quiet,” Gross said. “We’re not the type to attend functions and parties and galas. We like to work underneath, so to speak.”

Stamp Gallery

While Gross may donate with less fanfare than other billionaires, he’s hardly anonymous. There’s a William H. Gross Stamp Gallery at the National Postal Museum in Washington; a Sue & Bill Gross Stem Cell Research Center at the University of California, Irvine; and a Sue and Bill Gross Skywalk at the Cedars-Sinai Medical Center’s Advanced Health Sciences Pavilion in Los Angeles.

The couple, who live in Laguna Beach, California, do most of their giving out of a family foundation that mainly supports health care, medical research and education. They’ve also made personal gifts to needy American families. More recently, Gross said he’s taken an interest in GiveDirectly, an organization that makes targeted donations via mobile payments to the extremely poor in Africa.