This is shaping up to be 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. Some of the biggest investment banks on Wall Street are benefiting from the frenzy. In both its investment and trading divisions, "the teams are quite busy, and we feel great," Doug Petno, co-head of JPMorgan's commercial and investment bank, said at the same conference. At Jefferies, total investment banking revenue for the company's third quarter climbed to $1.1 billion, a 20% increase from the third quarter of last year.