LISBON, May 5 (Reuters) - Portugal's antitrust authority AdC ruled on Friday to fine the country's largest company, the utility EDP, 28.7 million euros ($31.54 million) and retail giant Sonae 9.6 million euros for an illegal non-competition pact between their subsidiaries.
Under the 2012 agreement, Sonae committed itself to not competing against EDP in electricity trading in Portugal for two years, the AdC said in a statement.
It said it had heard the two companies' defense on the matter and ended up confirming its earlier decision that the pact was illegal.
Sonae shares were 1.12 percent lower in late afternoon trading, but EDP was up 1.4 percent. ($1 = 0.9100 euros) (Reporting By Andrei Khalip, editing by Axel Bugge)