There are multiple credible reports in Korea that police are investigating an attempt to fix a fight at UFC Fight Night 79: Henderson vs. Masvidal on November 28, 2015, in Seoul, South Korea. There was an extraordinarily unusual flip in the odds before the event, with the fighter in question going from a -200 favorite to a +700 underdog. However, he ended up winning a Split Decision, which presumably allayed concerns.
Now reports are alleging that the fighter accepted a bribe of 100 million Korean Won (US$90k) to throw the fight by losing two rounds, and that the fighter also bet 50 million Korean Won (US$45k) on his opponent. The reports further allege that event management became alarmed by the sudden shift in the betting lines, and questioned the fighter, who denied all knowledge of anything untoward. According to this narrative, in response to the scrutiny, the fighter then changed his mind, decided to fight normally, and ended up winning. The fighter said further that word of his change of heart did not reach the fixers.
After the event, the fighter is alleged to have received threats, and responded by going to the police and admitting that he had agreed to take a dive. The police are now reportedly tracking down and speaking with the individuals alleged to be involved.
Note, this investigation is of a single fighter who allegedly colluded with gambling interests to fix a fight, but did not do so. Neither the opponent nor the promoter knew about the alleged fix.