The Los Gatos, Calif., company said Monday that it has adopted a shareholder rights plan.
Icahn disclosed his stake in Netflix Wednesday.
Under the plan, rights are exercisable if a person or group acquires 10 percent of Netflix, or 20 percent in the case of institutional investors, in a deal not approved by the board.
Netflix Inc. says its plan isn't intended to interfere with a transaction that's approved by its board.
Shares are down 99 cents to $75.91 in morning trading.