CHICAGO — A steel wire manufacturer and a steel processor have each moved up dividend payments, part of a trend among publicly held companies to allow shareholders to avoid a possible tax increase next year, according to an equities research firm.

The board of directors of steel processor, distributor and diversified manufacturer Worthington Industries Inc. has declared an accelerated third- and fourth-quarter cash dividend totaling 26 cents per common share. The dividend, payable Dec. 28 to shareholders of record Dec. 21, is in addition to the dividend announced Sept. 26 by the Columbus, Ohio-based company.

Last week, the board of Insteel Industries Inc., Mount Airy, N.C., which makes steel wire reinforcing products, declared a special cash dividend of 25 cents per share on Insteel’s common stock payable Dec. 28 to shareholders of record Dec. 19. The special dividend is in addition to Insteel’s regular quarterly cash dividend of 3 cents per share declared Nov. 13 and also payable Dec. 28.

"We elected to make this payment before the end of the year in view of the ongoing uncertainty surrounding future dividend tax rates," H.O. Woltz III, Insteel president and chief executive officer, said in a statement.

A dividend tax increase is a major concern for investors as the fiscal cliff approaches, according to Five Star Equities, a St. Kitts and Nevis-based research firm.

Major companies, such as Wal-Mart Stores Inc., have declared special dividends or have moved up quarterly dividend payments "in attempts to avoid the looming tax increase," it said.

Firms as diverse as truck manufacturer Paccar Inc. and the Chicago Board Options Exchange also have done so, AMM research shows.

The current top tax rate on dividends of 15 percent, set during the second Bush administration, are set to expire in January. If lawmakers fail to take action, dividends will be taxed at the same level as wages in 2013, Five Star Equities said.