Oil prices sank below $50 a barrel on Thursday for the first time this year, marking their lowest finish since late November, as the market worried that growing U.S. crude producers may undermine efforts to rebalance global supply and demand.

April West Texas Intermediate crude US:CLJ7 slid $1 or 2%, to settle at $49.28 a barrel on the New York Mercantile Exchange, after trading as low as $48.79 earlier in the session. Prices, which lost 5.4% a day earlier, finished at their lowest since Nov. 29, according to FactSet data.

May Brent crude UK:LCOK7 on London’s ICE Futures exchange lost 92 cents, or 1.7%, to $52.19 a barrel, also trading at levels not seen in more than three months.

Read:Oil’s tug of war gives way for a price collapse

Many analysts attributed Wednesday’s 5.4% plunge to a 8.2 million-barrel increase in U.S. crude stocks to a record level. It also marked the ninth consecutive weekly climb reported by the Energy Information Administration, which also revealed a rise in weekly domestic production to their highest level in more than a year.

In a separate report earlier this week, the EIA also raised its production forecasts for this year and next.

See:Here’s why U.S. oil data should rattle OPEC nerves

“It has obviously never been the intention of [Organization of the Petroleum Exporting Countries] to support the American oil industry, as this would reduce the impact of the lower OPEC production rate, and it’s now less likely the OPEC members will continue to honor the deal,” said analysts at Secular Investor, in a research note issued Thursday.

According to a report from Reuters Thursday, senior Saudi energy officials told top independent U.S. oil firms this week that they should not assume OPEC will extend their production cuts to offset output growth from U.S. shale fields.

Read:OPEC’s strategy to buoy oil prices is all wrong, oil economist says

Meanwhile, Ole Hansen, head of commodity strategy at Saxo Bank, said the recent drop for oil came as traders stopped betting oil prices will go higher and sold out of their long positions.

“The market psychology has changed, with longs now looking to reduce or get out. They were looking for a bounce to sell into, but as it failed to materialize, they resumed selling. Some short-term buyers looking for a bounce stopped themselves out once it broke below $50,” he said.

If crude breaks a key resistance level of around $47.18, prices could sink back to the November low of $42.20 a barrel, he added.

See:Oil baron Harold Hamm warns this one thing could ‘kill the market’

And:Why oil prices will never return to $100 a barrel, in one chart

Elsewhere on Nymex, gasoline for April US:RBJ7 slipped 2.8 cents, or 1.7%, to $1.624 a gallon, while April heating oil US:HOJ7 fell 2.7 cents, or 1.8%, to $1.530 a gallon.

Natural gas for April US:NGJ17 climbed 7.3 cents, or 2.5%, to $2.974 per million British thermal units. The EIA on Thursday reported that supplies of the commodity fell 68 billion cubic feet last week, larger than the 58 billion decline expected by analysts polled by S&P Global Platts. The data, however, included a “reclassification” of stocks.