Pair of portraits by Frans Hals expected to lead two-day sale of collection of Dutch entrepreneur, who was advised by the dealer Robert Noortman

Auction house sold the painting by Emma Sandys for £62,500 earlier this year, but now 19th century work is caught up in a legal battle

Now being sold by a London-based collector at Christie's New York, the work will probably go to Japan or China

Estimated at $300m, the sale of American Modernist masterpieces will be digitally encrypted by the blockchain startup Artory

Middle Eastern and South Asian works owned by embattled Dubai-based private equity firm carry much lower estimates than prices paid a decade ago

Francis Bacon's lighter depiction of George Dyer leads auction at £17.5m, with strong prices for Hurvin Anderson, Bridget Riley and Albert Oehlen

Profits from the sale will support new UK arts education programme in 2019

Our pick from this week's fairs and auctions

Move follows a record-breaking breaking year for Paris auctions in 2017

Portrait of an Artist (Pool with Two Figures) could become the most valuable work by a living artist sold at auction

Rubens’s portrait of his daughter Clara Serena gave me the urge to steal a painting

Our pick from this week's auctions and exhibitions

Rockefeller auction plus leap in private and online sales drive 26% increase

Tacca's Hercules is star of the bronzes, while Carracci's military portrait and Rembrandt's print find favour where Rubens's daughter flounders in £31.1m sale

Bronze and marble take centre stage during Old Masters sales week, although Dresden Mars returns home without going on the block at Sotheby's

Christie’s introduces day sale format and established names give way to new talent

Sotheby's sale fell below estimate while Christie’s provided some cheer, showing there is still money in Monet – but only the right one

The art world has yet to tackle issues around works like Picasso’s $115m child-prostitute portrait

Hostile relations between Russia and the West following attempted poisoning of former MI6 spy may dampen bidding at London's Russian sales

Still no evening auction, but blue-chip artists make way for fresh talent in new day sale format

New record for Joan Mitchell as fresh artists join the $10m-and-up club—but Bacon and Basquiat still dominate top prices in New York

Even without a $150m-plus headliner, the auction topped rival Sotheby’s by $100m thanks to deeper, more even bidding

Leaning on romance of Rockefeller name and its appeal to international and first-time buyers, the auction house triumphed in its marathon week of sales

The heads of Christie's, Bonhams and Phillips speak on market shifts, challenges and why they believe their model will succeed

Evening auction featuring the family's most valuable works set new records for Monet and Matisse

Sit back, relax, and follow the action from tonight's evening sale via tweet

Ahead of the sale of the David and Peggy Rockefeller collection at Christie’s this week, the family's archivist examines their approach

Painting of artist’s lover and muse comes to auction for the first time at Christie’s New York in May

The ritual objects include Mezcala and Chontal sculpture, plus Olmec stone celts

Exhibition targeted at Old Master collectors will not compete with the contemporary art event, auction house says