Stocks fell as speculation over interest rates hikes continued. The chances of a September rate hike has increased since Federal Reserve Chair Yellen took a hawkish turn in a speech on Friday. Crude oil was also pressuring markets. Prices extended losses after a weekly read on domestic inventories rose by just over two million barrels. The increase was far more than analysts expected. Pending home sales in the U.S. climbed in July to their second-highest level in a decade. Signed contracts to purchase existing homes have risen even as high prices and constrained inventory keep a lid on growth. Business activity in the Chicago area slowed as weaker global demand and a stronger dollar continue to impede the manufacturing sector. A nationwide read on manufacturing will be released Thursday.