By Jeremy Gaunt, European Investment Correspondent
LONDON, Sept 17 (Reuters) - Japan's aggressive intervention to weaken the yen has created a new climate for the euro just as investors' growing appetite for Europe's equities is set to be tested by new economic data.
Investors are also entering the new week bracing to see whether the Federal Reserve will embark again on quantitative easing, essentially printing dollars to create liquidity, a prospect that helped drive gold to new heights on Friday.
It all makes for a volatile week ahead, even if there are some signs of an end-of-year return of risk appetite.
The biggest disruption to current investment patterns came on Wednesday when Japan sold as much as 1.86 trillion yen ($21 billion) to weaken the currency in an attempt to protect trade competitiveness.
It has had the effect -- desired, as far as Japan is concerned -- of knocking the yen down to close to 86 yen to the dollar from a 15-year high of 82.87. But it has also made investors jittery. Another round of intervention could be forthcoming and will keep markets on edge in the coming week. There are come concerns that a flood of yen in the system could seek yield overseas and put pressure on emerging market currencies.
"The Japanese intervention in the FX market has implications for the (Japanese government bond) curve and in the currency markets way beyond the yen," BNP Paribas said in a note.
One of those currencies may be the euro. Less heralded than the yen's fall against the dollar, has been its impact on euro strength.
The European single currency rose nearly 5 percent against the yen in the three days following the intervention, which also fed the euro's September rally versus the dollar.
The euro has gained around 3 percent against the dollar in September and is above $1.30.
TEST FOR EURO ZONE
Such trends are not good news for the euro zone's exporters, which have been the backbone of the region's relative economic recovery and the outperformance of some of its bourses.
Investors have begun treating European equities as something of a proxy for emerging market growth, lifting the likes of Germany's DAX up more than 5 percent year-to-date while developed markets in general remain in the red.
Investment in the euro zone has also been supported by surprising economic resilience. But this is about to be tested. Wednesday sees the release of euro zone industrial orders for July and consumer confidence for September, while Thursday brings a raft of PMI manufacturing data for September and Friday sees the monthly Ifo survey on the business climate.
Nearly all are expected to show a decline, suggesting a slowdown in the euro zone.
"It is the usual pattern," said Jan Poser, chief economist at wealth manager Sarasin. "When the U.S. slows, people think that Europe is the place to be. But it just follows."
This is perhaps part of the reason why Reuters surveys in the past week showed expectations for U.S. equities to catch up with Germany.
The polls pointed to a gain of 7.4 percent for the DAX by year end, up from roughly 5 percent now but that the S&P 500 would end up with annual gains of 7.1 percent, compared with the current close less than 1 percent.
Some of that may also be related to expectations for a rally following the U.S. mid-term elections.
FED WATCH
Investors of all stripes will also be focused on the Fed's policy meeting, poised to see whether it will embark on further monetary easing to stimulate the sluggish U.S. economy.
While the consensus view is that there is no more than an outside chance that it will announce further quantitative easing after its meeting on Tuesday, partly because some data, including jobs, has been better than expected.
But any hint that more QE is on the way or that the economic outlook has worsened would generate more market volatility.
It could damage the risk rally that has been underway for much of September.
Will Bartleet, an absolute return fund manager with HSBC Global Asset Management, said QE would have had a fairly risk-positive impact on markets if it had been announce at the end of August. Sentiment is much more optimistic now, he said
"I think the risk (for equities) would be to downside and for bonds, the opposite," he said.