The most accurate way to invest and trade is to focus on the charts. It gives you the truth without any emotional hype. A bull flag is a bullish pattern of consolidation on a chart. When it appears, the stock price will often move up nicely in the coming days. This bull flag pattern is appearing on multiple big name biotech stocks. Gilead Sciences, Inc.(NASDAQ:GILD) and Celgene Corporation (NASDAQ:CELG), note the charts below.