Iberdrola to fund U.S. buy with cash call, shares dip

Iberdrola said the deal would give Energy East an enterprise value of 6.4 billion euros and Iberdrola one of around 83 billion euros.

"The U.S. represents an important growth opportunity, and the acquisition of Energy East is a step forward in our strategy to create an Atlantic platform," said Galan.

Analysts on the conference call expressed concern that Iberdrola will not get an easy ride from regulators in the U.S.

Del Valle said the company had already had preliminary contacts with regulators and stressed that Iberdrola was going into the transaction to invest in the U.S. power system.

"This is not a synergy-based transaction and it's not tax- based," he said. "It's to bring us into the U.S. market with investment -- that's what the regulators are interested in."

By 1000 GMT Iberdrola shares were 2.3 percent lower at 41.90 euros -- the biggest loser on the Ibex 35 index which lost 0.3 percent.

The DJ Stoxx European utilities sector index stood 0.5 percent lower.