One of Claude Monet’s large waterlily paintings sold for a world record £41 million last night, heralding a week of London art sales that could raise more than £500 million.

An anonymous buyer bought Le Bassin aux Nympheas for what was a record price for the artist at auction. The auction house, Christie’s, had estimated that it would fetch £24 million.

Last night’s Impressionist and Modern Art sale confirmed that museum-quality art is now regarded as an asset to investment portfolios rather than a luxury purchase. As another large sale prepares to start tonight, art experts acknowledge that record prices are being paid thanks to an exotic new breed of buyer whose tastes are reshaping the most rarefied end of the art market.

At Sotheby’s, the most fashionable look in the international art market is being flaunted along one wall. There are five oils, all painted between 1904 and 1907: two bridges by Maurice de Vlaminck, beach scenes by Albert Marquet and Edvard Munch and July 14 in Le Havre by Raoul Dufy.

Each one is a riot of unrestrained colour. Tonight, if the auction house’s hunch is right, they will sell for far in excess of their estimated combined price of £9.6 million, itself double what they would have fetched five years ago. The bidding is expected to be dominated by City hedge fund owners, Russian billionaires, Chinese industrialists, Indian technology entrepreneurs and Middle Eastern sheikhs.

These are the darlings of the art world, decisive and apparently impervious to market rates. Twenty-one per cent of lots at Sotheby’s Impressionist, Modern and Contemporary sales last year went to new buyers.

Helena Newman, the vice-chairman of Sotheby’s Impressionist and Modern Art department, said yesterday: “People’s choices are now being driven by image rather than the artist’s name. We’ve never seen a period where the bidding showed such a range of tastes.

“They want to look at their pieces, enjoy them and show them off. Colour and strong bold compositions are grabbing them and these are the sort of collectors for whom the estimate price is just a starting point.”

Bold, early 20th-century paintings with “wallpower” have been smashing records in New York and London. They include Weidende Pferde III by Marc, which sold for £12.3 million in London, £4 million above the estimate; Munch’s Girl on a Bridge, which sold for $30.8 million (£15.6 million); and Lyonel Feininger’s Jesuits III, which raised $23.2 million. There have also been new records for Monet and Rodin in the same period.

It boils down to a stand-off between the two behemoths of the auction world, which could soon be resolved.

The outcome may involve the other talking point ahead of this week’s sales, Roman Abramovich. Will the newest entry to the top of the market make a bid, and if so what for?

Melanie Gerlis, of The Art Newspaper, said: “The art market is not huge, so you only need a few collectors like Abramovich to transform it.”

Monet: impressions of an artist

— Claude Monet (1840-1926) gave Impressionism its name with his 1872 painting Impression: Sunrise but is now best known for the works he made in the last 30 years of his life in his garden at Giverny, 45 miles northwest of Paris

— He painted more than 250 oils in the garden, including images of apple trees, willows, irises and a distinctive Japanese bridge. However, it was the lily pond that provided his richest source of inspiration

— The most celebrated works in the Waterlilies series are the eight giant installations glued to the walls of the Orangerie in Paris, which the artist created for the nation after the First World War

Source: Times research

Editor's choice

• The 100 Best Films of the Decade
• 70 facts you didn't know about Marvel
• The 50 Biggest Movies Of 2010