U.S. crude oil extended its five-day plunge on Thursday, wiping out this year's gains and falling toward the psychologically important $60 level.
U.S. West Texas Intermediate crude futures were trading at $60.26 a barrel by 4:18 p.m. ET, after the close of Thursday's session. WTI ended the final trading session of 2017 at $60.42.
Brent crude, the international benchmark for oil prices, gave up all of 2018's gains earlier this week. It was last trading at $64.24, down nearly 4 percent year to date.
Rising U.S. output and crude stockpiles piled pressure on oil prices over the past two sessions, after commodities were swept up in a crushing stock market sell-off on Friday and Monday.