HTC has announced it is selling its remaining stake in Beats back to Beats Electronics, meaning that the Taiwanese smartphone manufacturer will no longer own any of the audio company.

HTC invested in Beats, adding Beats Audio branding to a run of handsets in 2011, but the deal never really got going. Bundled Beats headphones were limited, before reverting to standard HTC headsets and the Beats Audio boost never really offered anything more than what sounded like a tweak to the bass.

HTC sold 25 per cent of the company back to Beats in 2012, and now returns the final slice with the two companies heading off in different directions.

HTC says in its investor statement that "HTC and Beats will continue to partner as future opportunities arise", which is vague enough to mean just about anything.

Turning to the positive, in the same statement, HTC talks up its own BoomSound speakers, which debuted on the HTC One, saying: "HTC BoomSound has been developed by HTC's sound engineers with an unparalleled attention to detail and has evolved to a point to deliver the best possible mobile sound."

READ: HTC One review

The deal does, however, return $265 million into HTC's coffers.

Beats has also announced a minority investment from The Carlyle Group, with the aim of expanding the brand and business globally, although the details of the investment remain undisclosed at this time.

"We are confident that Beats will continue to drive innovation and growth in the premium audio accessory market, particularly as the proliferation of smart phones and tablets stimulate increased consumption of digital media," said Sandra Horbach, Carlyle MD and head of consumer and retail. "Carlyle has a strong history of helping great brands expand globally, and we are thrilled to partner with Jimmy Iovine, Dr. Dre and their talented management and product teams."