In 2000, the DOJ sued to block what would've been the largest merger in American history if it had gone through, a ~$120b combination of Sprint and WorldCom.
Thanks. I couldn't find a list of the largest blocked mergers, just of the largest successful ones (topped by AOL/TimeWarner). Pretty amazing how many of the large mergers turned out. WorldCom tanked two years later, so that would have been another combined failure.
