FBI officials quietly approached executives at Coca-Cola Co. on March 15, 2009, with some startling news.

Hackers had broken into the company's computer systems and were pilfering sensitive files about its attempted $2.4 billion acquisition of China Huiyuan Juice Group, according to three people familiar with the situation and an internal company document detailing the cyber intrusion. The Huiyuan deal, which collapsed three days later, would have been the largest foreign takeover of a Chinese company at the time.

Coca-Cola, the world's largest soft-drink maker, has never publicly disclosed the loss of the Huiyuan information, despite its potential effect on the deal. It is just one in a global barrage of corporate computer attacks kept secret from shareholders, regulators, employees — and in some cases even from senior executives.