According to a Perpetuum dev blog, the fraud came about when players figured out how to game the insurance system. The game's robots are insured not according to a fixed amount, but in relation to the global market average. Developer "Zoom" explains what happened next: "Due to some additional flaws in the mechanism, with good skills and good facilities it became very profitable to manufacture robots with the sole purpose of insuring them and blowing them up as soon as they roll out of the factory."
While the dev team initially sanctioned the action as part of a free market economy, this post represents a changed stance toward such practices. Players have written to Massively telling of how their wallets were sucked completely dry by the company after months of what they assumed to be legitimate market techniques.
The team retrieved over a billion NIC (Perpetuum's currency) from players and called out a number of corporations involved in these actions. Ultimately, the team elected not to ban any of the associated parties for the time being. Instead, all players should be seeing a modified version of this insurance feature within the week.
[Thanks for all the tips sent in on this one!]