West Texas Intermediate crude headed for a sixth weekly decline, the longest stretch of losses in 15 years, as rising U.S. supplies countered speculation that the Federal Reserve will maintain stimulus of the economy.

Futures have fallen 0.5 percent this week, poised for the longest streak since December 1998. U.S. crude stockpiles climbed for an eighth week as output expanded to the highest level since January 1989, data yesterday from the Energy Information Administration showed. WTI rebounded today after Janet Yellen, the nominee for Fed chairman, said yesterday the central bank shouldn’t end its asset-purchase program too soon.

WTI for December delivery advanced 36 cents, or 0.4 percent, to $94.12 a barrel at 10:18 a.m. on the New York Mercantile Exchange. The volume of all futures traded was 32 percent below the 100-day average.

Brent for January settlement declined 12 cents to $108.16 a barrel on the London-based ICE Futures Europe exchange. The December contract expired yesterday after rising 1.3 percent to $108.54. Volume was 12 percent lower than the 100-day average.