Christie's Impressionist and Modern Evening sale continues several themes already visible last week and reconfirmed in Sotheby's sale on Monday. The market, especially the market for high-quality or distinctive works by name artists, remains quite strong. But it is stronger at the lower levels—a theme that is not new in the broader art market but may be newer in a Impressionist and Modern market flush with fresh supply—but selective at the upper reaches with sellers asking the fullest value upfront.

The two top lots in Christie's sale, the Malevich and Brancusi, are a case study. Both were offered with the same estimate level, a very considerable $70m. Both had impeccable museum credentials, the Brancusi had been on long-term loan at the Met for decades and the Malevich had been at the Stedelijk museum before it was restituted in 2008. Both sales can be rightly considered once-in-a-generation opportunities at a time when art buyers have more money than opportunities to buy world-class works.

The works also offer a contrast in selling strategies. The Brancusi was sold by the heirs of the original buyers who purchased the work in 1955 directly from the artist for a few thousand dollars. "This is what you call fresh to market," Judd Tully remarked drily in his ARTnews report. Despite the incontestable windfall, the family chose to take a third-party guarantee. They locked in their gains with the trade-off of leaving some money—$187,500, to be precise—on the table. (Update: Several experts on guarantees, including the advisor who worked on the Brancusi guarantee, have pointed out that the consignors did not sacrifice the $187,500. That money comes from the auction house's premium. And they are correct. We regret getting carried away with the rhetorical construction.)

The Malevich was took the opposite tack. A seller comfortable with risk, the Nahmad family, offered the work without any financial guardrails. Selling "naked"—to use a term the art market likes to pretend is common parlance—was seen as validating the market, as this quote from Katya Kazakina's Bloomberg piece illustrates: