With investors already assuming the Federal Reserve will lower its benchmark interest rate on Tuesday, the question has become: How much?

 Will the Fed lower its current overnight borrowing rate of 5.25 percent by the widely anticipated 25 basis points? Or will it aim for 50 basis points, to make a statement about its concern for the overall economy?

While only one of the two key inflation measures that are being released this week will come out before the Federal Open Market Committee meeting, data for both the producer price index and consumer price index in August are expected to augur for a rate cut.

 P.P.I. is scheduled to be released on Tuesday morning, and is expected to have fallen 0.1 percent after a 0.6 percent jump in July. The core number, considered a more accurate indicator for inflation, is seen as matching the 0.1 percent growth achieved in July.

 C.P.I., which will be released on Wednesday, is expected to remain unchanged in August after a 0.1 percent rise in July. Core C.P.I. growth is forecast as flat with July's, expanding 0.2 percent in the month of August.

 Also out on Wednesday will be August housing starts data, which economists expect will indicate that the housing market continues to stagnate. New home starts are seen as edging down slightly for the month of August to 1.36 million units from 1.381 million in July, with number of building permits also dropping in August, to 1.35 million units from July's 1.373 million.

 On the earnings front, the string of banks reporting third quarter results this week will be watched particularly closely. Morgan Stanley announces third quarter financials on Monday, Lehman Brothers on Tuesday, Goldman Sachs and Bear Sterns on Thursday.

 The Wall Street Journal notes that one reason why investors will be keen to pore over the reports in detail is to look at accounting specifics that only recently began to be disclosed in these statements.

 Under a new accounting rule, firms now distinguish between assets that have real market prices and those with valuations based on models and management guesswork. So investors will be able to glean a better sense of the bank's investment positions, as well as how accurate they can consider reported results.

 Shares of all four of the financial services players are down significantly for the year, but investors will be looking to Goldman Sachs and Morgan Stanley for at least reasonably good earnings performance this quarter.

 Recent layoff announcements have made for pessimism about Lehman Brothers, and Bear Sterns is the most vulnerable of the bunch to the current mortgage market troubles.

 As Wall Street digests an abundance of new data, Capitol Hill will also be buzzing with economic discussion this week. On Wednesday the Congressional Joint Economic Committee will hold a hearing on whether the subprime lending fiasco poses a threat to the broader economy.

 Witnesses are scheduled to include Congressional Budget Office director Peter Orszag as well as Yale economist Robert J. Shiller.

 Finally, Friday is a “quadruple witching day,” when the expiration of four different options and futures contracts, each of which occurs quarterly on a Friday, will coincide this week.

The phenomenon could create sudden spikes and dips in the market (as well as in trading volume) as some investors exercise their derivative positions, or roll them forward, at the last minute.

 Most September stock index options and some index futures, including the Standard & Poor's 500 futures, cease trading on Thursday and settle at Friday's opening. Individual stock options, options on the S&P 100 index, and single stock futures go off the board after Friday's close.

 Thursday Dutch bank ABN Amro holds an Extraordinary General Meeting which allows shareholders to discuss offers submitted by Barclays and the RBS, Santander and Fortis consortium.

 Former Federal Reserve Board Chairman Alan Greenspan releases memoirs on Monday. Book charts Greenspan's career and ends with a "searching look ahead" at the world economy, said Scott Moyers, the book's editor.