Billionaire hedge fund manager Bill Ackman on Wednesday said his firm has purchased more than 3.1 million shares of Netflix Inc. /zigman2/quotes/202353025/composite NFLX +1.98% , making it a top-20 holder. "The opportunity to acquire Netflix at an attractive valuation emerged when investors reacted negatively to the recent quarter's subscriber growth and management's short-term guidance. Netflix's substantial stock price decline was further exacerbated by recent market volatility," said Ackman, who is chief executive of Pershing Square Capital Management. He announced the investment on his Twitter account and in a press release . Netflix was not immediately available for comment.