June 9 (Bloomberg) -- The euro may decline to as low as 114.91 yen after failing to break through a key technical resistance level against the Japanese currency, according to Commerzbank AG.

“Euro-yen has been capped by the 55-day moving average at 117.85,” Axel Rudolph, a senior technical analyst in London, wrote in an e-mailed report today. “A drop to the March-to-June uptrend line at 115.91 now seems probable.”

The 17-nation currency strengthened 0.4 percent to 116.95 yen as of 11:15 a.m. in London. It rose to 117.85 yen yesterday, before closing at 116.51.

Should the currency pair fall below 115.91, “the 50 percent Fibonacci retracement of the March-to-April advance at 114.91 will be back in the picture,” Rudolph wrote.

In technical analysis, investors and analysts study charts of trading patterns and prices to predict changes in a security, currency or index. A resistance level is an area on a chart where analysts anticipate orders to sell a currency may be grouped, while a support level is where they anticipate buy orders to be clustered.

Fibonacci analysis is based on the theory that prices rise or fall by certain percentages after reaching a high or low.

--Editors: Daniel Tilles, Mark McCord

To contact the reporter on this story: Keith Jenkins in London at Kjenkins3@bloomberg.net

To contact the editor responsible for this story: Daniel Tilles at dtilles@bloomberg.net