That's not an IPO date at all. I think you're out of your depth here. The starting date can come from a splitoff, a floatation without an IPO, a simple name change, a merger etc.
It took me over a month to build a 98% correct 10-12 year IPO database, it's not easy if you insist the data is correct.
Nasdaq resources are hopelessly broken after the re-design. I informed them twice, over a month ago on how their dividend calendar is cutting off the first member of each dividend page (if the items are split into pages, as they always are now). So the dividend calendar is always incomplete due to piss-poor web designers.
It's even worse when you inform them of the problem multiple times and they don't even bother to respond, never mind fixing it.
If a major stock exchange in the world cannot even design a website with proper tables, what's left to be said?
