The latest milestone in what has been an already brutal year for markets? Every one of the 30 companies that make up the Dow Jones Industrial Average is worth less today than it was at the start of the year.

On an afternoon in which the Dow at one point shaved 500 points from its average before rebounding, some of America’s biggest-named companies like International Business Machines (IBM) and Exxon Mobil (XOM) suffered large losses in their market values.

Analysts are chalking up the broad decline in stocks to fears that the continued decline in commodity prices are signaling a weaker global economy than we had previously expected. And though soft commodity markets are worth keeping an eye on, market observers like Paul Sheard, Chief Global Economist at Standard and Poors rating services argue that much of the commotion in an overreaction that isn’t supported by the underlying data.

“What was the “raw material,” so to speak, that has been fueling the market discounting process in recent weeks?” he asks. “Our global economics team has not reported any major shift in the trend of economic data–even in China, the epicenter of global market angst. Recent market moves appear to be more sentiment- than data-driven,” Sheard argues in a note to clients Wednesday afternoon.

But even if investors are overreacting to fears of a global slowdown, they may have better reasons for selling the individual Dow components. IBM shares fell sharply, for instance, after it forecasted weak earnings roughly $1.50 per share less than analysts were expecting. The company cited weak software sales as more firms move their operations to cloud-based services as a reason for the forecast. America’s largest oil company, Exxon also fell sharply over investor concerns of weakness in the oil market.

Not every Dow component was down for the day, as UnitedHealth Group Inc (UNH) shares rose, though it’s stock was still down overall for the year.