What financing method makes a company declare an initial public offering (ipo)?

When a company makes its shares available to the public for business purposes i.e buying or trading.

Explanation:

There are many set of standards that a company has to meet for make such financing. These specifications are set by various exchanges and SEC. This sort of financing enables companies to gain capital by selling their shares in the primary market.

Different investment banks are hired for this purpose. These banks endorse and set demands along with price or date etc. These banks are called underwriters while such companies are called issuers.