This look at the first half of 2018 market share by artist was prepared with data from Blouin Art Info. It is available to AMMpro subscribers. Monthly subscriptions begin with the first month free. Feel free to subscribe and cancel before you are billed.  Blouin Art Info has done some calculations to conclude that Christie's, Sotheby's and Phillips together have sold $5.682bn in art during the first six months of 2018. It's worth noting that Arttactic has separately released numbers that put the combined figure of the three auction houses at $6.911bn:

ArtTactic said Christie’s and Phillips have gained market share in the period: Phillips reported auction sales rose to $511.8m (£386m), up 59% from the same period a year ago, while Christie’s grew 27% to $3.6bn, and Sotheby’s rose 11.3% to $2.8bn.

We're not here to referee between the two calculations when we can simply wait until both Sotheby's and Christie's release their numbers on the first half sales. For our purposes here, we can all agree that sales totals are up across the board. As a general rule of thumb, the art market does more business in the first half of the year than the second, primarily because the first half contains more sales cycles with London hosting March and June events and New York's Spring event often featuring the most ambitious lots. This year saw the additional sales 'season' of the Rockefeller collection in New York which might further skew the sales figures toward the first half of the year. The Rockefeller estate also seems to have had a strong effect on Christie's overall sell through percentage for the first half. This is worth noting simply because Christie's has made a point of corporate strategy to increase sell-through rates as a way to demonstrate value to buyers. Though of the three houses, Phillips seems to have posted the best sell-through rates, no doubt a feature of their small and targeted sales. Blouin's numbers offer us the opportunity to run some quick market share calculations: