For much of Tuesday, June 2, the second floor of Sotheby's Manhattan headquarters was off limits. Security guards turned away employees hoping to access the floor, which is where the auction house stages its biggest and most closely watched auctions—including the record-breaking Gustav Klimt painting. According to sources familiar with the matter, even senior staff were left wondering what exactly was going on upstairs.

The answer, it turns out, was a Jackson Pollock. Sotheby’s quietly organized a private auction for Number 19, 1951, a monumental work owned by Arne Glimcher of Pace Gallery, asking $50 million. The sale was conducted with an unusual degree of secrecy, and despite the efforts to keep it hidden, Oliver Barker, Sotheby’s chairman for Europe, was spotted walking around Midtown on Tuesday afternoon.

According to sources, Sotheby’s could not find enough bidders to get the auction off the ground. The painting was hardly hidden from public view. Number 19, 1951 was included in the Museum of Modern Art's landmark Pollock retrospective in 1999 and more recently appeared in an exhibition organized by Tate Liverpool.

The timing seemed favorable, as just three weeks ago, S.I. Newhouse’s 11-foot-wide Pollock sold at Christie’s for $181.2 million. However, the asking price of $50 million was seen as optimistic, and the sale ultimately failed to go ahead. The painting remains with Sotheby's.