Stimulus programs such as low interest rates and the Fed's monthly purchases of USD85 billion in assets suppress borrowing costs across the economy and make stocks an attractive buy.
At the close of U.S. trading, the Dow Jones Industrial Average finished up 0.15%, the S&P 500 index fell 0.19%, while the Nasdaq Composite index fell 0.59%.
Chemical giant DuPont and technology Dow component United Technology released second-quarter earnings earlier that beat expectations, though disappointing data in Netflix, Peabody Energy and other reports helped offset gains.
Trading was largely quiet, as investors awaited fresh signs to indicate when monetary stimulus measures may unwind.
On Monday, the National Association of Realtors reported that existing home sales in the U.S. fell 1.2% to 5.08 million units in June, missing market calls for sales to rise 0.6% to 5.25 million units in June.
Sales for May were revised down to 5.14 million from a previously reported 5.18 million.
The report added sales were up 15.2% from June of last year, while average house prices jumped 13.5% on a year-over-year basis.
While the numbers indicated that recovery continues in the housing sector, markets concluded the figures were soft enough to sway monetary authorities to keep stimulus programs in place for now, which are bullish for equities.
Leading Dow Jones Industrial Average performers included United Technologies, up 2.97%, Hewlett-Packard, up 0.98%, and Wal-Mart Stores, up 0.89%.
The Dow Jones Industrial Average's worst performers included The Travelers Companies, down 3.77%, McDonald's, down 0.82%, and Cisco, down 0.62%.
European indices, meanwhile, finished lower.
After the close of European trade, the EURO STOXX 50 fell 0.09%, France's CAC 40 fell 0.43%, while Germany's DAX 30 finished down 0.20%. Meanwhile, in the U.K. the FTSE 100 finished down 0.39%.
On Wednesday, the U.S. is to release official data on new home sales, a leading indicator of economic health.