If you were wondering how Netflix would respond to activist investor Carl Icahn taking a stake in the company, this morning you got your answer.

The company's board of directors adopted an antitakeover plan intended to block Icahn from expanding his nearly 10% stake in the streaming video and DVD-by-mail company. Under the plan, Netflix's shareholders will be given the right to acquire more stock if any individual investor acquires more than a 10% stake in the company, commonly referred to as a poison pill.

"Adopting...