"The Informant" starring Matt Damon - Trailer

Usual 'dramatic licence' but based on a true story.   You can read the book BY Author: Kurt, Eichenwald

Mark Whitacre, a high-level employee at ADM (Archer Daniels Midland), the "supermarket to the world", wears an FBI wire to uncover a major price-fixing scam. ADM pleads guilty and pays a $100 million fine, however Whitacre ends up doing more time than the corrupt leaders he helped to capture.
The Book:

INFORMANT; THE (MOVIE TIE IN) (ENGLISH) (PAPERBACK)

The Informant is Mark Whitacre, a senior executive with America's most powerful food giant, who put his career and his family's safety at risk to become a confidential government witness. Using Whitacre's secret recordings and a team of agents, the FBI uncovered the corporation's scheme to steal millions of dollars from its own customers. But as the FBI closed in on their target, they suddenly realised that Whitacre wasn't quite playing the game they'd thought - This is the gripping account of how a corporate golden boy turned into an FBI mole, and went on to double-cross both the authorities and his employers in one of the most extraordinary cases of global corporate corruption in the last thirty years.