If MasterCard if found guilty of violating EU antitrust rules, it can be fined up to $740 million or 10% of its 2012 revenue. Six years ago, the European Commission blocked MasterCard from charging cross-border card fees in Europe after an investigation. EU regulators are investigating Visa ( V) Europe's card fees as well. The chatter on Main Street (a.k.a. Google, Yahoo! and other search sites) is always of interest to investors on Wall Street. Thus, each day, TheStreet compiles the stories that are trending on the Web, and highlights the news that could make stocks move.-- Written by Brittany Umar.