At the Reuters Health Summit expect exclusive interviews with Merck CEO Richard Clark, AstraZeneca CEO David Brennan and Tenet CEO Trevor Fetter.

Other highlights:

* Treasury Secretary Timothy Geithner begins a two-day official visit to Japan ahead of the Asia-Pacific Economic Cooperation finance ministers’ meeting in Singapore on Thursday.

* Diversified U.S. manufacturer Tyco International reports third-quarter results. Wall Street expects another drop in profit as the ongoing soft economy saps demand for industrial products.

Expect results from sector heavyweights McDonald’s, AT&T, Merck, 3M and Amazon.com.

*  Microsoft launches Windows 7, hoping the new operating system will erase the memory of Vista.

*  American Express is expected to post lower earnings for the third quarter, as more consumers fall behind in their payments and spend less.

*  Amazon.com reports third-quarter results. Any comments about the upcoming holiday season could be market moving.

*  When AT&T reports results, investors will be looking at whether it continues to gain ground on the strength of the iPhone.

*  Merck and Bristol-Myers Squibb post quarterly results and give clearer hints how well the drug industry has withstood the global economic downturn, even as insurers keep reining in drug prices.

*  Analysts expect diversified manufacturer 3M to report a drop in profit as the slumping global economy saps demand.

*  McDonald’s, a favorite among investors, is expected to report results showing why it is the biggest of fast-food companies, even as unemployment and rampant discounting puts pressure on the fast-food segment.