I like how the of DD shares have quieted down over the past few days here, which can signal that the sellers are done with their selling for the time being.
The way to put this trade on is to wait until the DD starts to outperform SPY on a given day and THEN put the trade on. It's a simple rule to follow when putting on PAIRS trades.
Remember the old saying: Buy SHEEP, Sell DEER.
(Translates to Buy Cheap, Sell Dear)
"Dear" means when everyone loves something.
4:06PM EST 9/15/2015
Banking the gain.