Another law firm has filed an investor suit against Motorola Inc., claiming executives didn’t tell the market how bad things were last fall as sales began to slow.

Schiffrin Barroway Topaz & Kessler LLP filed suit last Wednesday in U.S. District Court for the Northern District of Illinois on behalf of investors who bought Motorola shares between July 19, 2006, and Jan. 4.

Motorola’s shares peaked at $26.30 on Oct. 13. On Monday, the stock price was below $17 per share.

The suit claims Motorola did not disclose problems with its product line and geographic challenges in Europe that led it to miss its forecasts in the third and fourth quarters.

Named in the suit are CEO Edward Zander; Ron Garriques, former head of mobile devices; David Devonshire, former chief financial officer; Greg Brown, then-executive vice-president of networks; Daniel Moloney, president of connected home solutions; Richard Nottenburg, chief strategy officer; and Padmasree Warrior, chief technology officer.

“We will vigorously defend ourselves against these claims,” a Motorola spokeswoman said.

Executives, excluding Mr. Zander, sold more than $26 million worth of stock during the period, according to the suit.

The Schiffrin law firm is based in Radnor, Pa. Last month, the law offices of Bernard Gross, based in Philadelphia, and Brodsky & Smith of Bala Cynwyd, Pa., each filed suit, also seeking class-action status.