A simple analysis of trading psychology that was recently happened on EURUSD.
1. Price broke through the upper trendline, breakout players jumping in and start buying the pairs.
2. The big players(institutional, hedge funds, etc) let the market ran for a while to wait until a lot of bulls entered the market.
3. Most of novice traders are easy to read, so the big players can predict their entries and stoploss. In this case, most of the entry and stoploss triggers are probably set on these 2 lines.
4. Once the bullish momentum slowly built up, those big players started pouring sell orders in huge chunks, drowning all the retail traders who had taken buy position thinking the breakout would continue.
5. Price slowly going down even though most of traders were sure the breakout was a sign that price might go higher. Some novice might have thought that this bearish movement was just some retracement before price launch like a rocket.
6. The institutional traders, this time, managed to push price down until it started hitting the stoplosses of the retail traders. A stoploss of a long position equals as a sell order when triggered.
These triggered stoploss, combined with new sellers that jumping in after seeing a strong selling pressures, can only fuel the bearish momentum even more, resulting in an even bigger selling pressure.