Edit:
1.The bitcoin hacks, March 2012
2.HTP hack, April 15, 2013 (CF exploit)
3.Second HTP hack April 16, 2013 (Another CF exploit)
4.MySQL server that allowed anonymous logins (?!?!) January 19, 2014
5.This hack
I'm not counting their domain name and various other parts of their infrastructure provided by third parties being compromised, but if I was the list would be significantly longer.