The stock market just can't hold on today.

The S&P 500 was down 0.2%. The Nasdaq Composite dropped 0.3%. The Dow was up just 16 points, or flat, after trading up more than 200 points.

There wasn’t an obvious catalyst for the slide, though the major indexes all dropped while Bloomberg TV aired an interview with DoubleLine Capital CEO Jeffrey Gundlach. The bond-fund manager echoed recent comments from JPMorgan Chase CEO Jamie Dimon, arguing that a “reckoning is coming” for U.S. Treasuries.