U.S. stocks closed lower Wednesday, the last trading day of the month, as investors digested falling oil prices and looked ahead to Friday's jobs report.
"We didn't get a lot of information today, and part of what we're trading on were the higher-than-expected oil inventories," said Kim Forrest, senior equity analyst at Fort Pitt Capital. "A lot of our clients are looking at September and are a little worried."
The S&P 500 fell about 0.25 percent, as energy and materials fell more than 1 percent and nearly 1 percent, respectively. Energy extended losses after after the Energy Information Administration said inventories rose by 2.3 million barrels last week. U.S. crude futures settled 3.56 percent lower at $44.70 a barrel.
"Basic materials, especially metals, are also tanking. Some of the areas that were giving support to the market are not doing well," said Chuck Self, CIO of iSectors.
The Nasdaq composite fell about 0.2 percent, as the iShares Nasdaq Biotechnology ETF (IBB) dropped 0.85 percent.
The S&P snapped a five-month winning streak, while the Dow ended a six-month winning streak. The Nasdaq rose 0.99 percent in August.
"I think there's a real trepidation surrounding Friday's number," said Quincy Krosby, market strategist at Prudential Financial. "The report we get for August is often weaker than expectations. You don't want a much weaker number that suggests the economy is weakening, but you don't want a much stronger report."
Private companies added 177,000 jobs in August, according to the latest report from ADP and Moody's Analytics. Economists polled by Reuters expected a gain of 175,000.