Colin Gleadell calculates Christie’s mid-year results release and does his homework on Sotheby’s site to make these observations. At Christie’s, the pain was not shared equally:

Dubai (down 70 per cent) and the UK (down 62 per cent), were the worst hit regions. British and Irish art sales (including Victorian, Scottish and 20th-century art) shrank more than any other category, by a steep 80 per cent.

Gleadell then gets out a sharp pencil and pokes around Sotheby’s website to do these sums (bullets added by AMM):

Sotheby’s is not due to announce its results until next Tuesday. Comparisons will be complicated by the fact that while Christie’s has made its calculations in sterling, which minimises the downturn because of changes in the exchange rate, Sotheby’s will do so in dollars.

• A preliminary inspection of Sotheby’s website indicates that, with the exception of Paris, similar falls have taken place globally
• there has been an average downturn of 67 per cent in sales
• from $3 billion (£1.5 billion) last year, to just under $1 billion this year.
• The percentage drop will be trimmed, possibly to 60 per cent, by the addition of sales made after auctions, and by private sales which are not detailed on its website.
• When calculated in dollars, Christie’s sales downturn increases from 35 per cent to 49 per cent.

Art Sales: This Year, It’s All About Yves (Telegraph)