A:
If these companies are most likely safe and avoid going against Allah's Purified Shar` (Law), there is no harm in buying shares in them. You should also do your best to know the truth before dealing with them as Allah (Glorified and Exalted be He) states:
So keep your duty to Allâh and fear Him as much as you can
May Allah grant us success. May peace and blessings of Allah be upon our Prophet Muhammad, his family and Companions!