Wouldn't the simplest/most obvious answer be arbitragers "fairly...

Wouldn't the simplest/most obvious answer be arbitragers "fairly certain the scheme is going ahead." somehow they must have some sort of inside info that the transaction will proceed. I can't see any spoilers coming in from China able to get past FIRB, the current proposal from SQM will pass FIRB and Chris Ellison is not in the business of screwing over Gina Reinhart.

I agree with the posters here in that Ellison selling this stake is much less interesting than who bought this stake.....