William Gross, manager of global bond giant Pimco, has announced plans to auction off his collection of classic British stamps and donate the entire proceeds, projected to be as much $5 million, to Doctors Without Borders, the New York Times reports.

Gross said his decision to sell a portion of his vast stamp collection was based both on his feeling that the market for British stamps had reached its peak and on his and his wife's desire to make a significant contribution to a humanitarian cause. According to Dr. Darin Portnoy, the president of the U.S. affiliate of Doctors Without Borders, the proceeds generated from the auction could be one of the largest donations in the organization's thirty-six year history.

While Gross, who is the only collector known to own at least one copy of every U.S. stamp ever issued, intends to continue adding to his American collection of classic stamps, he said his British collection would provide a "good source of funding for charity."