Over the past year, on days when the euro was up it was also likely that U.S. stock exchange traded funds were rising. However, in the first half of March, U.S. stocks and the euro have been moving in opposite directions as the dollar strengthens with equities.

SPDR S&P 500 (NYSEArca: SPY) is up 2.3% in March, while PowerShares US Dollar Index Bullish (NYSEArca: UUP) has gained 1.8%. CurrencyShares Euro Trust (NYSEArca: FXE) is off 2%.

Kimble Charting Solutions notes that over the past two years, the S&P 500 and the euro have shown a high degree of correlation. However, the relationship broke down during the fourth quarter of 2011, when stocks and the euro were moving in different directions. [Euro, Stock ETFs Go Their Separate Ways]

The non-correlation is showing up again in March.

“It’s the polar opposite of what happened last August,” says Paul Weisbruch, vice president of ETF/options sales and trading at Street One Financial, referring to the summer sell-off that was led by weakness in the euro. Now, investors appear to be less concerned with the euro, which marks an “interesting” change, he said. It could mean the market is moving past its obsession with the European debt crisis.

“Over the last ten years, we have grown accustomed to rallies in equities being accompanied by a weak dollar, but over the last two weeks, both the dollar and S&P 500 are up,” says Bespoke Investment Group.