Citibank is the latest in a string of high-profile businesses to report it has been hacked. A limited number of Citi North America bankcard customers’ account information was exposed. Social security numbers, expiration dates, birth dates, and social security numbers were not compromised. Experts say phishing and social engineering attacks against the affected Citi customers are the biggest threats. Citi has some 21 million cardholders in North America, which would mean that 200,000 or so were compromised.”]