After launching IPO

You can do it in banks as well for private listed companies.

Regarding this, I only know two or three concepts, public issue, private issue and private placements. 

All three will incur issue costs. 

Then public issue stocks can be traded directly in primary, secondary markets and private issue stocks can be traded in secondary markets. Primary markets are stock exchanges and secondary can be brokers, financial institutions etc. 

The private placement means, the company will issue shares to its own acquaintances, partners or existing shareholders.