The plunge followed news that the audit committee of Symantec's board had launched an internal investigation into undescribed concerns raised by a former employee. The probe is being aided by independent counsel and other advisers, the company said in its fiscal fourth-quarter earnings report.

Symantec said it had informed the US Securities and Exchange Commission of the probe and intends to share information collected during the investigation with the commission. The outfit said it cannot predict the duration or outcome of the investigation, Symantec said it's unlikely that the probe will be completed in time for the company to file its annual 10-K report for the fiscal year ended March 30, 2018, in a timely manner.

CRN said that the that the investigation "is not tied to any security concern or breach around Symantec's products or systems, Cynthia Hiponia, vice president of investor relations, said during the company's earnings call Thursday".

Sales in the fourth fiscal quarter ended March 30 jumped to $1.22 billion, up 9.6 percent from $1.12 billion a year ago. On a non-GAAP basis, revenue increased to $1.23 billion, up 4.9 percent from $1.18 billion last year.

The company reported a net loss of $35 million, improved from the $143 million loss,  the year before. On a non-GAAP basis, net income skyrocketed to $310 million  up 68.5 percent from $184 million, last year.

For all of fiscal 2018, Symantec's revenue climbed to $4.85 billion, up 20.6 percent from $4.02 billion in fiscal 2017. The company recorded net income of $1.16 billion up from a net loss of $106 million last year.

Enterprise security sales tumbled to $609 million, down 7.2 percent from $656 million the year prior as an acceleration in the adoption of cloud and subscription-based products by enterprise customers led to lower in-period revenue recognition.

Consumer digital safety revenue, though, increased to $613 million, up 33.6 percent from $459 million last year as customers move beyond device security and focus on protecting the entire life cycle, according to Symantec.