Get more investment news at Annuity News Now While a flood of merger-and-acquisition activity will eventually be a boon for the biggest U.S. investment banks, the last 18 trading days of September are more important for their earnings in the near term. While merger advice has been a feast, trading on Wall Street has lately been a famine. Given that trading has become the lifeblood of Wall Street's investment banks, both companies at the moment are looking at lower income in the third quarter. How much can the booming M&A make up for weak trading? Very little, it turns out. Less