May was a good month for the majority of public companies that are based in Iowa or have significant operations here, with 22 of the 36 posting gains in stock prices.

That’s the good news. Year-to-date numbers show that 50 percent of Iowa companies have experienced a decline in stock price.

Biofuels and pharmaceuticals apparently were attractive last month. Renewable Energy Group Inc.’s stock price jumped 15.4 percent and closed at $10.63 a share on May 29, the last trading day of the month. For the year, REG’s stock has gained nearly 20 percent, posting an increase of $1.94 a share.

KemPharm Inc., a newcomer to the list, posted an 11.6 percent increase in stock price to $12.32 per share. KemPharm was added to the list in April. It is one of 22 Iowa-based companies that are tracked by the Business Record.

Dice Holdings Inc. and Voya Financial ranked Nos. 3 and 4, respectively, and topped the list of companies that are based out of state but have key operations in the state. Dice stock gained 11.45 percent in May, while Voya gained 7 percent. For the year, Dice stock has dropped nearly 16 percent. Voya stock has gained 7 percent, or nearly $3 per share over that time.

The Iowa index, an unweighted average price of the 22 Iowa-based public companies we track, gained 0.69 percent in May and has increased 0.34 percent since the start of the year.

Other top gainers in May among Iowa-based companies were Casey’s General Stores Inc., up 6.1 percent, Winnebago Industries Inc., up 4.9 percent, Flexsteel Industries Inc., up 4.9 percent, and HNI Corp., up 4.0 percent.