Let's check the position of the charts and indicators again as we await the earnings report.
In the daily bar chart of COST, below, we can see that the shares have turned down from a high in August. COST is below the cresting 50-day moving average line and the declining 200-day line.
The On-Balance-Volume (OBV) line shows us weakness from the middle of August and tells us that sellers of COST have become more aggressive with heavier trading volume happening on days when the stock closes lower. The Moving Average Convergence Divergence (MACD) oscillator is below the zero line in sell territory.