What happened on wex.nz?
Wex.nz is formerly btc-e which was raided by US stazi and many bitcoins were stolen.
They re-opened as wex.nz with the promise that they would get everyone their coins over time. They created a token in place of your actual coins so that you could trade those with the promise that within 2 years (1 year from now) they would reimburse 100% of the coins tokens held.
Since they didn't have many of the actual coins they shut off withdrawals. But they allowed you to withdraw a few coins. One being namecoin. People with money on wex who want to get it off bought NMC so they could take it off the exchange and then sell it elsewhere.
This lead to a huge rise in price on wex of NMC and a huge crash in price everywhere else.