Stocks ended lower on Monday with indices extending losses to four consecutive days for the first time in 2013. Investors are bracing themselves for a week of significant economic data, including a highly anticipated announcement from the FOMC that many on Wall Street are expecting to contain an official announcement about the beginning of the Federal Reserve’s phased withdrawal from the bond market.

The Standard & Poor’s 500 index closed at a deficit of 0.59 percent to 1,646 points, while the Dow Jones Industrial Average finished 0.47 percent lower at 15,010.74 points, and the NASDAQ ended at 3,589.09, down 0.38 percent.

Wednesday will see the release of data on existing home sales, with economists expecting a modest increase in the area of 0.4 percent. The same day, the minutes of the monthly Federal Open Market Committee meeting will be released, with investors hungry for some guidance on the future of the Central Bank’s drawing-down of asset purchases.

Thursday will see the release of initial jobless claim figures, as well as the Kansas City Fed’s survey of regional economic expansion. Friday will provide information about new home sales for the month of July.

As usual, scrutiny of and concern over the contents of Wednesday’s FOMC minutes from the prior-months’ meeting are already dominating the landscape for equities, as investors spent a fourth straight day taking profits.

On the S&P 500, basic materials stocks were hit the worst as a result of news about lower natural gas prices that could negatively affect producers throughout the year. Marathon Oil (MRO) , Cliffs Natural Resources (CLF) , and Apache Corp. (APA) all ended the day almost 5 percent lower.

JPMorgan Chase & Co. (JPM) ended the day 2.75 percent lower on heavy volume after news that the bank was accused by the SEC of bribing the children of Chinese officials in an attempt to curry favor with the country’s state-run industries. Last week, the SEC said that it would seek to force the bank to admit to wrong-doing in last year’s London Whale scandal.

JPMorgan’s loss also put pressure on the Dow, all of whose components ended the day in the red, with the most significant losses for Alcoa ($AA) and Hewlett-Packard (HPQ) .

On the NASDAQ, biotech firm GTx Inc. (GTXI) dropped over 65 percent to $1.43 per share on news that the company’s tests of a highly anticipated anti-muscle loss drug enobosarm missed on all primary endpoint goals.

Apple Inc. (AAPL) ended the day over one percent higher to $507.74, as the company’s executives moved forward on long-standing plans to sell a significant number of their own shares, while Carl Icahn’s recent $1.5 billion stake was replicated by other hedge-funds and investors.

Otherwise, tech shares were a drag on the exchange, with Microsoft (MSFT) , BlackBerry (BBRY) , and Yahoo! Inc. (YHOO) among others ending the day lower on heavy trading.