Osram declined to comment.

Bain is working with financial advisers in assessing a business with a market value of almost 3.9 billion euros (3.46 billion pounds), the report said.

Bloomberg added that other potential suitors including rival buyout firms were also looking at the former Siemens unit, though the interest might not ultimately result in a deal.

Osram's shares were up 14.3 percent to 38.62 euros at 1045 GMT.

The Munich-based company has twice cut profit guidance this year, citing sluggish demand from automakers holding off buying LED lights amid uncertainty over new car testing standards and the trade conflict between the United States and China.

(Reporting by Thomas Seythal; additional reporting by Alexander Huebner in Munich; Editing by Keith Weir)