Calling NXT an "IPO"... is like calling a lottery an "IPO".
Yeah, I mean even today not many people would advise investing in a coin with no screenshots, no whitepaper, no working beta, no escrow, no source code, and an eccentric anonymous newbie dev who decides to go AWOL just days into its development* but for those people who took the risk and invested, well their risk taking definitely paid off.
Fun fact: 1 bitcoin invested into NXT in November 2013 would have been worth $5 million just by hodling for seven months. That same bitcoin purchased in the beginning of 2013 would have been worth $13.
*I'm not trying to disparage NXT or anything since it's actually one of my favorite altcoins and probably one of the most innovative. Heck, I even have a Coinomat sig!