Arrest for insider trading at LeoVegas related to purchase of MGM

According to Swedish media, a manager at LeoVegas and two accomplices have been detained for insider trading relating to the company's acquisition by MGM.
The main suspect was detained between 1 February and 29 April, according to the daily tabloid Aftonbladet, and MGM's initial offer for LeoVegas was made in May.

 

[GamblingBoy]

Insider trading, what does that mean?. I need explanation on this. Anybody with details should please give explain here. Until I get indepth details here, I reserved my comment.