Irish businessman Mr John Magnier is now one of the world's top 10 most active art collectors, according to the trade magazine, ARTnews.
Much of Mr Magnier's extensive collection is weighted towards equestrian art, according to a list to be published next week.
The New York-based magazine, considered one of the most reliable sources in the art world, places the worth of the collection owned by Mr Magnier and his wife, Susan, ahead of other well-known art collectors such as Microsoft chief Mr Bill Gates, advertising executive Mr Charles Saatchi and lawyer Mr Robert Shapiro.
The magazine does not order its top 10 list, but says it includes those who were still collecting in the last year. ARTnews editor Milton Esterow said Mr Magnier kept a low profile in the art world but was known for collecting equestrian as well as British and modern art.
Mr Magnier has made very significant purchases in recent years, including a painting by Italian artist Amedeo Modigliani for $26.8 million (€21.6 million) in New York last year, and Sir Joshua Reynolds's Omai for £10.3 million (€15.4 million) in London in 2001. The British government put an export freeze on the painting to stop it leaving the country, part of a drive to stop foreign investors buying up British art.
Mr Magnier, who started Coolmore stud in Co Tipperary in 1975, has been a long-time collector of equestrian art, but his taste has broadened as his personal finances have grown.
His love for modern art has carried into other areas of his life. He and fellow Irish racing tycoon Mr JP McManus acquired a 28.89 per cent share in Manchester United through their company Cubic Expression.
The world's most active collector is believed to be Sheikh Saud Al-Thani of Qatar. In recent years he has spent hundreds of millions of dollars on art.
ARTnews says its list of the 200 top collectors follows research by staff and correspondents who interview confidential sources among dealers, auction house staff and collectors.