Crude prices have been on a downward streak for days, first pushed down by the prospect that the decline in U.S. shale production since April last year could be reversing as the number of drilling rigs rises.

Brent crude, the global oil benchmark, fell 1.5% to $48.23 a barrel on London’s ICE Futures exchange. On the New York Mercantile Exchange, West Texas Intermediate futures were trading down 1.5% at $47.30 a barrel.

Global stocks have sold off in recent days amid fears that a British vote to exit the European Union, or “Brexit,” will disrupt financial markets and the economy. Opinion polls ahead of the June 23 referendum have narrowed in recent weeks.

On Thursday, the Stoxx Europe 600 dropped 1.3% in early trade as bank shares hit new lows, following a downbeat lead from Asian markets.

Analysts say that the market slump is feeding through oil prices.

“The increased chances of a Brexit could be a catalyst for weak market fundamentals feeding through into outright price declines,” analysts at JBC Energy said in a note to clients.

The U.S. Federal Reserve on Wednesday decided to keep interest rates steady, which weakened the U.S. dollar. A weaker dollar is usually welcome news for commodity prices, which are priced in the currency.

However, the dovish Fed action can also be interpreted as a sign that the U.S. central bank is becoming more cautious about economic growth. “Fed’s decision to leave interest rates unchanged (while turning dovish on future hikes) fed into growing fears over the global economy,” JBC said.

Also on Wednesday, the U.S. Energy Information Administration reported that domestic crude stockpiles shrank less than expected, decreasing by 933,000 barrels. Stockpiles also grew by 525,000 barrels at the key crude delivery hub of Cushing, Okla.

However, production fell by 29,000 barrels to 8.72 million barrels a day. It had risen the previous week.

“While the outlook for global oil fundamentals remains constructive, with slight global crude and product draws expected in the second half of this year, the current mood in the oil markets is risk averse, and the U.S. weekly report didn`t do anything to change that,” say analysts at Société Générale.

The apprehension among investors is that as prices climb, more U.S. producers will be lured to drill new wells or complete the ones that were halfway developed before the price plunge. The number of rigs drilling for crude has risen for two straight weeks

The production increase two weeks ago, along with rising rig counts, “may have been a bearish signal to some market participants,” analysts at Credit Suisse said in a report.

Nymex reformulated gasoline blendstock—the benchmark gasoline contract—fell 1% to $1.49 a gallon. ICE gasoil changed hands at $432 a metric ton, down $9 from the previous settlement.

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