You are right that $4B from an IPO is technically another fundraising round.
However, an IPO is a special case, as for years now a company/its board will consider an IPO as a business strategy decision and not as fundraising per se.
Big shift in the 1980s.
There are some legal/regulatory aspects to an IPO and "liquidity event" type reasons an IPO is treated differently too.
Basically, an IPO brings many pros and cons with it. A company may choose to IPO even when it doesn't need the cash or even want the cash. The money raised is just a byproduct of choosing this particular business strategy.
(An analogy in pre-IPO startups: A startup may take an investment from a famous or influential VC even though the startup doesn't need the money at that point. Rather they look at it as a business decision because the startup really wants some other benefits they can get from having this famous VC as an investor. e.g. mentorship, network connections or even just more legitimacy by association... Lots of VCs provide non-cash benefits but you have to take cash to get them.)
As for how did Snap Inc. get that $4B number. That's complicated and not even an official number. But a simple answer could be if a company's current private valuation is ~$40B and they want to IPO for strategic reasons but only sell off/dilute as little as possible while still looking respectable.
They won't IPO only 1% of the company, too little, 10% is a respectable minimum. 10% of $40B = $4B.
Total speculation and just an example. But hopefully you see you are right to ask questions when these companies IPO as it's full of smoke and mirrors with a different story behind the scenes.
However, an IPO is a special case, as for years now a company/its board will consider an IPO as a business strategy decision and not as fundraising per se. Big shift in the 1980s.
There are some legal/regulatory aspects to an IPO and "liquidity event" type reasons an IPO is treated differently too.
Basically, an IPO brings many pros and cons with it. A company may choose to IPO even when it doesn't need the cash or even want the cash. The money raised is just a byproduct of choosing this particular business strategy.
(An analogy in pre-IPO startups: A startup may take an investment from a famous or influential VC even though the startup doesn't need the money at that point. Rather they look at it as a business decision because the startup really wants some other benefits they can get from having this famous VC as an investor. e.g. mentorship, network connections or even just more legitimacy by association... Lots of VCs provide non-cash benefits but you have to take cash to get them.)
As for how did Snap Inc. get that $4B number. That's complicated and not even an official number. But a simple answer could be if a company's current private valuation is ~$40B and they want to IPO for strategic reasons but only sell off/dilute as little as possible while still looking respectable.
They won't IPO only 1% of the company, too little, 10% is a respectable minimum. 10% of $40B = $4B.
Total speculation and just an example. But hopefully you see you are right to ask questions when these companies IPO as it's full of smoke and mirrors with a different story behind the scenes.