New York ? A drop in industrial production and a profit warning from McDonald’s Tuesday took a jab at investors’ already shaky confidence in the economy, prompting them to again sell off stocks. The Dow Jones industrials fell more than 170 points.

“We saw some credible evidence that the economy is still sluggish in the production number, and we saw credible evidence that corporate earnings are going to remain weak with the McDonald’s warning,” said Arthur Hogan, chief market analyst at Jefferies & Co.

The market’s biggest obstacles, earnings and the economy, “are still with us,” Hogan said.

Companies that warned of weaker profits were among the losers. McDonald’s slid $2.78 to $18.91, to a low not seen since October 1995, and Kroger dropped $2.25 to $15.76. Both companies cut their yearly growth estimates, and Kroger missed fiscal second-quarter earnings expectations.