Art experts, dealers and collectors are all stumped about who made the purchase, which set a record by far for any artwork and included $50 million in buyer fees.

"We do not comment on the identities of the buyers, I'm sorry," said Christie's CEO Guillaume Cerutti. "The bids came from every part of the world."

Christie 's, which sold the work Wednesday, is bound by the usual confidentiality agreements and can't say anything about the buyer.

The $450 million sale of Leonardo da Vinci's "Salvatore Mundi" has touched off an epic guessing game in the art world: Who would pay so much for a painting?

Some dealers say the buyer is likely an American, since there is only one da Vinci in the U.S. — currently at the National Gallery in Washington — and it would make sense for a billionaire to buy it and donate it to a museum in New York or L.A.

Others say the price suggests it was a foreign buyer willing to pay anything to have a da Vinci in, say, China or the Middle East.

"This feels to me like it was someone who wanted to bring the only Leonardo to Asia," said one major collector. First, the sheer price of the painting rules out most everyday billionaires. Anyone who pays nearly a half billion for a painting is likely to be worth at well over $5 billion and most likely over $10 billion. That rules out all but around 150 of the world's more than 2,000 billionaires, according to wealth experts.

And while there are no credible reports on who the buyer might be, some of the most obvious candidates can be ruled out.

There has been some speculation that the buyer was hedge-fund billionaire Ken Griffin, who purchased a de Kooning and Jackson Pollock for a combined $500 million and lent them to the Art Institute of Chicago. Griffin wouldn't comment but sources in the art world say he was not the buyer of the da Vinci.

Another American candidate was Alice Walton, the Wal-Mart heiress who has spent hundreds of millions to fund the Crystal Bridges Museum of American Art in Arkansas. The museum didn't immediately comment, but people close to the museum said "not likely."

With overseas buyers, some have speculated that it could have been Liu Yiqian, the Chinese billionaire who purchased a Modigliani for $170 million in 2015 to put in his new Shanghai museum, called the Long Museum. But on Thursday, Liu posted a message on WeChat saying he wasn't the buyer. "Congratulations to the buyer. Feeling kind of defeated right now."

One other possibility is the world's richest man, Jeff Bezos. He certainly has the cash. Aside from being worth $95 billion, Bezos sold $1 billion worth of stock in early November and didn't announce a use of the proceeds. Of course, the cash could be going to fund his Blue Origin aerospace company or a new philanthropy initiative. But that cash would have also been able to easily buy the da Vinci, which he could then donate to a museum in Seattle or wherever Amazon decides to put its new headquarters. As a fan of history and other geniuses, Bezos would see the piece as far more than a painting.

A spokesperson for Amazon didn't immediately respond to a request for comment.

Whoever purchased the painting isn't likely to be able to keep it a secret for long. Such a high profile purchase in the age of social media and gossip is hard to keep under wraps. And the price suggests that the buyer is likely to want to put it in a museum for all the world to see. More than 27,000 people flocked to see the piece as it made its way around the world as part of Christie's marketing campaign. Let's hope the new buyer opens it up to the public again.