U.S. airlines tumbled the most in three months as concerns mounted that President Donald Trump’s ban on travel from seven predominantly Muslim nations will lead to more restrictions on flights. Investors are fearful that the U.S. curbs will expand or be answered with retaliation by other nations, said Joe DeNardi, an analyst at Stifel Financial Corp. Trump already has signed an order to pull the U.S. out of the Trans-Pacific Partnership trade accord and said he wants to restructure a 23-year-old pact between the U.S., Mexico and Canada.