The Art Newspaper points out that Christie’s half a billion dollars in private sales so far in 2015 is off by a third from last year. That raises the possibility that Christie’s super-charged auctions have been cannibalizing their private sales (a turn-about from previous conventional wisdom.)

private sales—which previously seemed to be on a relentlessly upward trajectory—showed a steep fall fr om the £500m ($828m) recorded in the first half of 2014, coming in at £333m ($515m) this time around. In a statement, Christie’s said that it was still “on track for a record year” in this category, with a “significant pipeline” expected in the second half of the year (the annual total for 2014 was £916m/$1.5bn).

Christie’s sales growth cools in the first half of 2015 (The Art Newspaper)