The price action is a little more one-sided in shares of Amazon.com ( AMZN) -- and you don't have to be an expert technical analyst to figure out what's going on in this online retail giant. Amazon has been trading lower since late January, boxed in by a well-defined price channel that's in a downtrend. Its shares have hit their head on the last four attempts to move through resistance -- and there's no reason to think that the fifth time will be a charm. Price channels provide traders with high-probability ranges for a stock to trade within. Even so, it's important to stay reactionary in shares of AMZN. All trends end eventually, so it's worth waiting to see how shares act at their trendline before putting money on the line. If this stock bounces lower off of resistance today, I'd recommend being a seller (or shorting it). Amazon looks likely to keep trending lower in May. To see this week's trades in action, check out this week's Must-See Charts portfolio on Stockpickr. -- Written by Jonas Elmerraji in Baltimore.