That came after the German lighting group’s biggest shareholder - Allianz Global Investors - on Thursday rejected the 3.4 billion euro (£3.16 billion) takeover offer.
The SdK said it also held shares in Osram and would not tender them. The recommendation carries weight because around 25% of the company is in the hands of more than 440,000 private individuals.
Osram’s managing and supervisory boards had said on July 4 that they were backing the offer, pitched at 35 euros a share, a 21% premium to Osram’s share price before the approach was made public.
Reporting by Joern Poltz; Writing by Tom Sims; Editing by Michelle Martin