Not all of the big trades worth watching are bullish setups right now. Oil and gas supermajor Exxon Mobil ( XOM) is a good example of another huge name that's been doing its best to drag the broad market lower since November -- and it looks likely to continue underperforming. That's because XOM is currently trading in a wide downtrending channel. Granted, the downtrend in Exxon may be shallow, but it's no less real -- and with shares coming down off of resistance this week, it could have considerably lower to fall, especially if the commodities Exxon owns continue to flounder. For traders looking for a shorting opportunity in this stock, it makes sense to make a bet as shares are moving down off of resistance. I'd recommend keeping a protective stop just above the top of the channel. 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.