Tipster n. One who makes a practice of giving or selling tips, or private hints or information, esp. for use in gambling upon the probable outcome of events, as horse races.
... lures of the "System's" hirelings, the decoy calls of the market tout and the financial tipster whose part it is to mould opinion and urge the people to the shambles. Before my eyes, with a blind and audacious defiance of my warnings, the old, old game was rigged in full view of the audience and the old players began their venerable antics. ... — Frenzied Finance - Vol. 1: The Crime of Amalgamated • Thomas W. Lawson