It looks to me like betting by speculators as to which companies are the most likely candidates at this stage to be bought out.

Noront being the biggest land holder with very interesting and sizable resource holds is likely to be last of the potentials. The smaller companies that have demonstrated to be holding interesting resources or being in close proximity to good ones ( have great potential) are easier to be aquired. So any speculator holding Noront now, would sell Noront and buy one or more of the others.

It would take the likes of Vale or Xstrata to take out Noront and even Cliffs chromite assets but the likelyhood of that happening right now must be low. The more likely chance is that Cliffs will continue to aquire one at a time most demonstrated resources with Noront being at the end.
A big cap will take interest when most of the resources of the Ring will be under one or two ownerships. They usually are not interested in picking up scraps but size of demonstrated and ready for market resource is what they are after.