US shale is getting in the way of a New Year's resolution by OPEC to cut production and boost the market.

Producers and merchants increased their bets on lower West Texas Intermediate crude prices to the highest level since 2007 as futures held above $50 a barrel. The increase in hedging against a price drop signals a comeback in US shale output, just as OPEC members and other producers seek to reduce supply.

In November, the Organization of Petroleum Exporting Countries reached an agreement to cut production by 1.2 million barrels a day for six months starting in January, and were joined by 11 non-OPEC nations in an effort to reduce a global glut. Last week, the Energy Information Administration raised its forecast for next year's US crude production. A Barclays survey showed North American oil and gas explorers will spend 27 percent more this year.