Betfred will not renew its sponsorship of the British Classics, which include the Derby, the Oaks and the St Leger, and has blamed tax rises for the betting industry, City AM reports.
A Betfred spokesman said the firm, owned by Fred Done, had taken the "difficult decision not to proceed" with a three-year renewal. The spokesman cited successive tax rises for the industry and in particular the increase to machine games duty at the most recent Budget.
City AM says Healey announced a 5% increase to machine games duty at the Budget on 28 October. It says this makes a 25% hike in total when added to an earlier 20% rise by Rachel Reeves. These figures are City AM's own account and have not been independently checked against the Budget documents.
City AM adds that Betfred earlier pulled out of sponsoring rugby's Super League, which it says cost the sport £1m a year.