After IPO, it`s common that corp value drop.
When state corp changes to public corp, it pays country resource instead and profit actually went down sharply after IPO.
You might try to increase the profit, or if the corp becomes truly public, profit will increase, but in the initial IPO, profit always drop and value drop.
IPO to your own enterprise is one way to retain all the profit within your own empire although the value of the corp will still drop.