According to The Economist, the speculation is on three people: Leonard Blavatnik, a financier, Paul Allen, Microsoft tycoon/horrible person, and members of the Qatari royal family. CultureGrrl added that the Sotheby's man who made the bids for the winner (who phoned in his bid) usually represents Americans.
Meanwhile, Forbes agrees with me that the purchase wasn't worth it as an investment -- pointing out that only about 5 people in the world have both the wherewithal and the ability to pay more than $119,900,000 for a painting. Since 1 of them already did, that leaves four left. If one of them buys it, that leaves only three other people currently alive who might be able to repurchase the painting and get a return on your investment.
Then again, maybe "return on your investment" could be realized by having crowds of people line up to see it: Sotheby's put on a huge marketing campaign (they won't say how much they spent trying to get people to spend money on The Scream) and part of that packed people into museums, so sending the painting (the world's most-stolen artwork) on tour might generate income to pay off some of that purchase.
But back to the 5-living-potential purchasers: Am I the only one who senses a Dragon Tattoo-esque thriller in that setup? DIBS ON THAT STORY!
I hope they cast Rihanna
in the movie version of this painting!