I've been betting on USDJPY rising for a few weeks now...basically since the earthquake... clearly it hasn't worked... Moreover, the inability to decisively bounce off 80 despite the prior BoJ intervention and persistent Japan negativity has even made me flip over to a short USD.JPY position (long JPY). Taking a loss is never easy when you become committed to some longer term macro view, and I rarely ever "stop and reverse" but I've seen the scenario play out numerous times over the years. It suddenly became clear to me that almost everyone is positioned the same way (yen shorts). Just as I had, I strongly suspect others are viewing the downside capped by prior (and future?) FX intervention, and that creates a confluence of sell stops that are just waiting to be triggered. Whilst Japan may intervene to prevent "excessive" fx volatility, I'm not sure they're really committed to defending a particular level such as 80 in USDJPY. I can only imagine at the extent of the sell stops in USD that have built up in 75-78 range. The longer stocks stay weak, the more pressure the JPY shorts will come under. In addition, JGB futures also look primed to burst up through 141.00 after trading in a really tight range in recent weeks, and typically when you get short covering in JGBs (often reflecting dumping of "Sell Japan" plays by foreigners) you often get corresponding short covering in JPY. When I checked out the Tokyo Financial Exchange retail fx positioning data and read that 88% are long USD.JPY I realized I had to fade that.