Dax investors are treading water on the first trading day following the Easter break. The German benchmark index opened 0.1 percent higher at 23,195 points on Tuesday. "Lead-ins from Wall Street remain positive despite ongoing uncertainties," said Andreas Lipkow, analyst at broker CMC Markets. For now, the U.S. ultimatum against Iran remains the dominant market theme. "There still seems to be little movement in negotiations between the warring parties, and military confrontations continue."

Trump has set a deadline of Tuesday evening for Iran to reopen the Strait of Hormuz. Should no agreement be reached by then, the U.S. military will reportedly destroy all of the country's power plants and bridges. Iran recently rejected a U.S. proposal for a ceasefire mediated via Pakistan, demanding instead a permanent end to the war.

(Report by Stefanie Geiger, edited by Sabine Ehrhardt. For inquiries, please contact our editorial team at berlin.newsroom@thomsonreuters.com (for politics and economics) or frankfurt.newsroom@thomsonreuters.com (for companies and markets)