Trigger? I would call it instant spike on Draghi's comment (half of the move) ...On the renko chart it seems obvious, but actually it wasn't as abvious, except the extremely overbought conditions of the EURUSD pair.
The signal was given the 8th of may ...the currency pair dropped.
But it's history.
The signal was that stoch moved under 80, but didn't give you and idea of how hard or target..
That's simple.... maybe to simple for some of us. ;)