There were a couple assets bigger than NEM but they were entirely within the NxT system, e.g, NxT holders buying the new assets (NxT to assets). NEM, although hosted on the same asset exchange, brought in new people who were paying premium prices for NxT in order to buy NEM (BTC to NxT to NEM).
Sianote was a third party IPO. The issuer made like close to 2 million Nxt in two or three days, and developer ended the IPO