Scottish Grand National-winning jockey Richie McGrath is among seven who have been charged with breaching betting rules.
McGrath and former trainer Kate Walton are alleged to have passed on inside information about the likely performance of horses in order to manipulate betting.
The duo, who will face the British Horseracing Authority's disciplinary panel, are believed to have conspired with Mark Aspey, Carl Flint, Kristian Robson, David Stevens and/or David Greenwood.
It has been confirmed by the BHA that the investigation relates to 57 races that took place from October 2009 to April 2012.
A provisional hearing has been scheduled for November 11.
