for IOTA i see it has only been alive on exchange for 2 days and only on bitfinex for some reason. and in this 2 days it has already dropped ~43%
after ico, tokens were traded ofc and on NXT AssetExchange for months. then there was an own slack channel trading established which worked really fine.
IOTA would have been on Polo and Kraken if they had managed to integrate it in time. now it is on their priority list and should be listed soon.
The fact that it went down on bitfinex is mainly due to their problems in integrating the new architecture, but the problem has been solved today and price is already recovering (still red as most of the alts due to btc crash)