On the hourly timeframe, the decline in GSK beginning in Aug 2016 can't be counted as an impulse for sure. Maybe it's a leading diagonal that I'm not seeing, but I believe probabilities are best interpreted as a WXY pattern as labeled.
Which implies it is a 2nd X wave down in a larger WXY (Ending Diagonal) pattern depending on how you interpret the Feb lows. I anticipate the potential for a Bullish reversal at the Red Oval 41.21 ending in 5 waves down for leg c of y of X.
My plan is to catch it on the way up if divergence exists, or late on positive reversal first pullback with a Lower Blue descending trendline break. Long trade up into the Green Oval near 46.50. Initial stop below wherever the c leg terminates near 41.27.