Other sources about the event covered by the article also don't use "the biggest":
http://online.wsj.com/articles/judge-allows-sac-capital-insi...
"Mr. Martoma was found guilty in February of making illegal trades in what prosecutors have called one of the most lucrative insider-trading schemes in history."
Note "one of the most lucrative."
Note that the amount involved is just $276 million:
http://www.rediff.com/money/report/indian-origin-fund-manage...
Orders of magnitude less than what Bernie Madoff did:
http://en.wikipedia.org/wiki/Madoff_investment_scandal
"$64.8 billion"