Most startups don't raise multiple rounds in the same year.
(An extreme example to prime your intuition: imagine that there are one IPO and 10 VC deals annually. If every startup raises money annually and there are 10 startups at any one time, then every funded startup eventually IPOs.)
Ignore mine.
It wouldn’t be called “IPO” anymore, but a company can offer subsequent market shares through a Follow-on Public Offering (FPO.) This occurs when a business raises capital in a second round of stock through either dilutive or non-dilutive options. Good to know.