Gigaweek at the New York auctions began with news from Sotheby's of a quarterly loss, followed by a boost from an announcement of investor interest and mixed results for its Monday sale.

A wider-than-expected first-quarter net loss of $25.9 million in the quarter on revenues of $106.5 million — compared to a profit of $5.1 million on $155.7 million in revenue during the first quarter of 2015 — was first announced. 

Then came news that an investor might take partial control, a stake as much as 10 percent, of Sotheby's. The publicly-traded auction house, with a market cap of around $1.6 billion, has seen shares drop by about 40 percent in the past year. After the investor news, stock gained 6.5 percent to $29.03 at 2:54 p.m. in New York.

Sotheby's CFO Mike Goss said on a call, "We've recently been advised by an outside investor that they may make purchases of our stock whether through the open market, privately negotiated transactions, block trades or derivative transactions to bring their holdings to at least 10 percent of the shares outstanding, and that they've filed the necessary documentation under the Hart-Scott-Rodino Act that would allow them to do so."

He added that, "Of course, they have no obligation to purchase stock and they could decide for any reason not to do so."

The Impressionist and Modern Art sale later Monday had Auguste Rodin’s L’Éternel printemps, an embracing couple in marble, sell for $20.4 million, setting a new auction record for the French sculptor. Turn of the 20th century masterpieces – including works by Vlaminck, Signac and Monet – pushed the sale to a total $144.5 million, far short of its $164.8 million low estimate. Of 62 lots, 21 went unsold.