New Delhi, July 25 -- BRUSSELS - Alphabet's stock slid on Friday as the European Commission levied its largest Digital Markets Act fine yet - roughly one billion dollars split between Google's search and app store operations - and President Trump threatened Brussels with tariffs before the EU's announcement had finished clearing the wires.

Executive Vice President Teresa Ribera announced a penalty of 860 million euros, approximately $1 billion, split between 460 million euros for Google promoting its own services in search results over rivals and 400 million euros for restricting app developers from directing users to cheaper alternatives outside the Play Store. Google had sixty days to achieve full compliance or face additional fines of...