comparisons.

What I find increasingly bemusing is the comparision of SDL with other IO explorers.
MMX has just announced an incr3ease in reserves to 70 million tonnes DSO with 455 million BSO and is rated at $1.5 billion market cap and 50% of the resource is mitsubishi.
SDL has a first resource statement of 190 Million tonnes DSO and estimates 1.2 billion tonnes BSO yet its market cap is around $450 million with 90% of the resource being SDL.
Project timetable seem to be 4 years earliest before MMX get into production and SDL one would think will definately be a producer by then.
Can anyone please explain there theory on the market caps ?