A pumpjack brings oil to the surface in the Monterey Shale, California, U.S. April 29, 2013. Photo: Reuters, Lucy Nicholson

High-beta oil companies are dragging down the S&P 500, with Marathon, Chesapeake, Devon, and Transocean accounting for the largest point drops in the broad index. Marathon is down by 7%. Oil is “cuspy” at the current price of $48; that’s just the level at which a significant amount of shale production turns profitable.