This is turning into the year of the mega deal for Wall Street bankers. Thus far companies have announced 49 global M&A transactions valued at more than $10 billion, according to Mergermarket, the highest such count for so-called "mega deals" through the first nine months of any year ever. These transactions include the$55 billion leveraged buyout of Electronic Arts (EA) announced Monday, Union Pacific's (UNP) $85 billion merger with rival railroad Norfolk Southern (NSC) in July and Google's (GOOG)$32 ...