Audio-equipment maker Monster LLC and its chief executive sued Apple Inc.’s Beats Electronics LLC, its co-founders Jimmy Iovine and Dr. Dre, and Taiwanese smartphone maker HTC Corp. for allegedly conspiring to dupe Monster out of a deal with Beats before the company was sold to Apple for $3.2 billion last year.

In a complaint filed in Superior Court in San Mateo County, Calif., Monster said Beats “fraudulently acquired” the Beats by Dr. Dre line of headphones through a “sham transaction” with HTC, which agreed to purchase a 51% stake in Beats for $300 million in 2011.

The complaint asserts that Beats repurchased 25.5% of its own shares from HTC less than a month after the deal closed, allowing Beats to end its relationship with Monster due to a change-of-ownership clause.

Monster helped launch the Beats brand of headphones, a flashy and pricey line of music accessories that proved popular among celebrities and teenagers, in July 2008. Monster said it developed, manufactured and distributed the headphones in exchange for the licensing rights to the Beats brand and celebrity marketing by Mr. Iovine and Dr. Dre, whose real name is Andre Young.

Monster said the change-of- ownership clause triggered by the HTC deal required Monster to transfer all intellectual property to Beats, costing the company millions in lost revenue.