NEW YORK ( BBH FX Strategy) -- The euphoria over the eurozone's master plan appears to be short lived and risk aversion is once again taking hold in markets with Italy's 10-year on the run, with yield breaching 6% again and just a few basis points shy of the high seen in early August.As a result, European bank shares are broadly lower (down 2.7%), bund and gilt futures are higher and other periphery spreads are on the rise. S&P 500 futures also point to a weaker opening, down nearly 1%. Price action is also being driven in part by the USD/JPY fluctuations after the Bank of Japan unilaterally intervened during the Asian session, boosting USD/JPY to 79.55. However, heavy demand following the intervention forced the pair back to levels near 77.80. On the data front, German retail sales rose less than expected, while broad eurozone data such as unemployment and inflation were worse than expected, boosting demand for safe havens. Follow TheStreet on Twitter and become a fan on Facebook. Today markets are likely to focus on the aftermath of the unilateral BoJ intervention. Unlike the moves by the SNB, this did not target a specific level. As such, this suggests a rejection of the Swiss approach and more importantly suggests to us in time that these levels are unlikely to hold, with JPY strength likely to persist. Nevertheless, the timing of the policy makers was orchestrated quite well by catching the market off guard and stealing headlines at the beginning of a very busy week which culminates with the G20 Summit. Market sources suggest policy makers have sold nearly 3 trillion yen overnight, although these initial estimates are generally wrong. Formally, we will have to wait a few days until the transactions are recorded on the BoJ's balance sheet. Above all, what really matter is not ultimately the size but rather the fact of the interventions itself. And will it work? Given the market initial response a one-off unilateral is unlikely to work for long. For one, following the intervention the yen has begun to inch higher again while the Nikkei reversed all its gain to close the day down 0.7%. What's more, the history of previous unilateral intervention is also discouraging, while the potential for multilateral agreement over further intervention is unlikely ahead of this week's G20 Summit. Overall, despite the action taken by Japanese authorities we expect the underlying fundamentals to remain the driver of yen strength, notably demand for safe havens and reluctance by the Japanese to recycle its external balance, leading to the yen to retest levels near 76.