Fourteen of the 18 Iowa-based companies on the Business Record's Iowa Index posted stock price gains for the month. Five companies posted double-digit percentage gains. Only four Iowa-based stocks posted losses, all single-digit losses.

Renewable Energy Group Inc. had the largest gain of the month with a 26.52% increase. Winnebago Industries Inc. had the second-biggest gain at 15.22%. Art's Way Manufacturing Co. had the third-biggest with a 14.24% increase.

HNI Corp. posted the biggest percentage loss at 6.38%. Ames National Corp. had the second-biggest loss with a 6.29% decrease. Flexsteel Industries Inc. was third with a 2.43% decrease.

The Iowa Index, an unweighted average price of 18 Iowa-based public companies, increased 6.82% in January, compared with a 1.42% increase in the Nasdaq stock index and a 2.04% decrease in the Dow Jones Industrial Average.

The Iowa-based companies that make up the Iowa Index are in bold in this list of companies with sizable operations in the state.

See the full Iowa Index