3. Operation Payback

Date: December 2010
Victim:
 Visa, MasterCard, Amazon, PayPal, PostFinance 

When the U.S. Government demanded that WikiLeaks stop releasing top secret diplomatic cables to the public, a number of companies that supported WikiLeaks in the past turned against the website by freezing accounts and shutting down the site's servers. Anonymous decided to step in on behalf of Julian Assange's cause and declared war on Visa, MasterCard, PayPal for refusing to do business with WikiLeaks. On December 8, 2010, both Visa's and MasterCard's sites were taken down by the group.