With shares down 3.2% in morning trade, Facebook Inc. FB, +0.20% has entered bear-market territory. The stock has now fallen 22% from its record close of $217.50 on July 25, and will officially be in a bear market if it closes at that level. Many chart watchers say a new bear market starts after a fall of 20% or more from a bull-market high. Shares of Facebook sold off 19% in Thursday's session after the company delivered a sharp warning about its future revenue growth, and the stock dropped another 0.8% in Friday's session. Facebook's stock is down 2.7% so far in 2018, while the S&P 500 SPX, +0.29% has gained 5.3%.