GENEVA — The Swedish “Treskilling Yellow” retained its title as the world’s most expensive stamp when it changed hands at a private sale shrouded in secrecy, the auctioneer claimed Saturday.

The one-of-a-kind 1855 misprint was sold to a group of buyers who asked that their identities and the winning bid be kept confidential, said auctioneer David Feldman.

He declined to reveal whether the sale matched the 2.875 million Swiss francs (then about $2.3 million) price it set a record for in 1996.
“It is still worth more than any other single stamp” including the even older “2 Penny Post Office Mauritius Blue” that sold for 1.5 million francs (then $1.4 million) in 1993, said Feldman.

He added that both the price and identity of the buyers, who took part in the telephone auction against a single rival bidder, would likely become public knowledge eventually.

Noted U.S. stamp expert Robert Odenweller said it wasn’t unusual for buyers of such valuable items to keep details of the sale secret at first.