All your corporations are too young to be bought (I think they have to be a year old before CEOs can bid on them).
You also have far too many for your population size, which is why they are under-staffed and not turning a profit.
You should have no more than two corporations per 1 million population. For your population, you should have no more than 16 corporations. You should either close some, or bid on population on the Cash Market (My Simcountry > Cash Market > Bid coins for population transfer).