Cheap money. Plenty of people have had years to buy assets with cheaply borrowed money. The Fed increased interest rates, people started to unwind their positio

Cheap money. Plenty of people have had years to buy assets with cheaply borrowed money. The Fed increased interest rates, people started to unwind their positions in oil and the stock market, that sets off a self reinforcing cycle that pushes prices lower forcing more people to sell in order to break even or limit losses.