Four Iowa companies have been named among the most ethical in the world, according to the Ethisphere Institute. For the second year, Voya Financial Inc. made the list, which recognizes companies that define and advance the standards of ethical business practices. Other companies receiving the recognition are Deere & Co., Principal Financial Group Inc. and Rockwell Collins Inc. In addition, Voya Financial CEO Rodney Martin will participate in the Ethisphere Institute’s seventh annual Global Ethics Summit, which takes place Tuesday in New York City. The full list of the 2015 World’s Most Ethical Companies can be found online.