Energy shares drag Wall Street lower
(Close): Shares in oil companies dragged Wall Street lower after the price of crude fell again.
US crude dropped 4% to $40 a barrel after members of the Opec oil producers' cartel signalled they would increase output.
The Dow Jones itself fell 27.73 points to 18404.51.
Shares in SolarCity fell 7.4% after Tesla announced that it had reached a deal to buy the company for $2.6bn. Shares in Tesla slipped 2%.
US telecoms giant Verizon fell 1.6% after it announced plans to buy Dublin-based GPS firm Fleetmatics for $2.4bn. The announcement came the week after Verizon secured a deal to buy Yahoo's core business for $4.8bn.
Shares of US carmakers were mostly lower ahead of Tuesday's report on car sales in July.