Nike stock plunges and takes rivals like Under Armour and Adidas with it

• Nike's stock was down Friday after the company lowered its outlook.
• The company said it planned $2 billion in cuts, which could include layoffs.
• Shares of competing brands like Lululemon and Adidas also fell. 

Nike's stock was down more than 11% Friday after the company lowered its outlook and said it planned $2 billion in cuts, which could include more layoffs.