The optimistic mood on Wall Street is finding support in a pick-up in M&A activity.

Swiss drug maker Novartis is taking Nestle’s 77% slice US eye-care company Alcon for $39 billion. Yahoo!, meanwhile, is sending smoke signals to Microsoft that it wouldn’t be against a bid if the price is right.

According to CityWire in Britain, the FTSE 100 broke through the 6,000 level “on a flurry of major corporate merger and acquisition reports from across the Atlantic.”

“The deal-making market is a key to the health of the US stock market,” says Jason Simpkins.

“The US buyout market is about to enter a new phase as corporate takeovers pick up where private-equity firms left off last fall. During much of 2006 and 2007, it was the steady stream of private-equity buyouts and corporate mergers and acquisitions (M&A) deals that propelled the key U.S. stock indices to one record high after another.

“When the deals are flowing, investors are willing to pay more for their shares, figuring the odds for a nice payday are higher. And the deal market was white-hot through the middle half of last year. Private-equity firms had amassed huge war chests. They were buying stakes in big companies and were buying smaller companies outright.”