Here's "What to Watch on Wall Street" for Tuesday, September 30th. On the economic front, the S&P Case/Shiller Home Price Index for July is due out at 9 A.M EST. The expectation is that there will be no change. Housing data in the U.S. has been mixed lately so investors will be looking to the Case/Shiller index for a clearer read on the health of the housing market. After that, there is the important consumer confidence index out at 10 A.M. We expect it to move a touch higher from last month to 92.5 for September. On the earnings side, Walgreens is reporting before the bell. Analysts expect earnings of 74 cents a share. Walgreens' profit missed last quarter because their pharmacies under-performed and customer traffic was weak. But for fiscal fourth quarter, its sales are expected to top $19 billion.