At a simple level its supply and demand. We currently have a high supply and low demand (less travel during the winter months) which in turn drives down prices.

At a simple level its supply and demand. We currently have a high supply and low demand (less travel during the winter months) which in turn drives down prices. Lower prices, means the energy sector is making less, when it makes less, people don't invest because it won't make you any money. At a more complex level, you have a war between US oil producers and OPEC (Organization of the Petroleum Exporting Countries). OPEC wants to put the US oil producers out of business. The US producers have started to give OPEC competition, driving down oil prices. The result has been an oil boom to oil crash. Lots of companies that were hiring are not hiring and in some cases, cutting jobs. Cutting jobs impacts employment numbers, employment numbers affect investments, the fed rate and a whole host of other things. While the energy sector won't make the market crash by iteself per se, it will certainly drag it down and make investors a lot more skittish to put more money into the market - having the effect we're currently experiencing.