These foreign developments contributed to a 15 percent appreciation of the broad dollar since mid-2014, which, along with weak foreign economic activity, weighed on 2/7  BIS central bankers' speeches  U.S. export growth. Concern over the strength of foreign demand also contributed to a steep decline in the price of oil at around the same time.
Historically, lower oil prices have been a positive for U.S. growth, but the tremendous rise in domestic shale oil production over the past decade has created a powerful counterweight that has offset some of the benefit of lower prices. In the immediate aftermath of the decline in oil prices, investment in the energy sector fell off precipitously, pushing down aggregate investment as well.