The P/E ratio is explained in documentation. Essentially they have to be more profitable.
I've heard that having them hold product for awhile, then selling it all at once can do this. Haven't tried it.
But unless you have some plan to use your own CEO corps to buy the shares, it's not going to be worth it.
Only exception being weapons corps, on account of wanting cheaper Q330 weapons. There you can at least sell the shares to your population investment fund if you don't want 3 CEOs.
-hymy-