Sharp plunge? Are you forgetting SQM's back up off market offer of $3.50 that has no minimum acceptance condition?
I can't speak for SQM, but even if they manage to get >40% they will be able to exert significant influence in the direction of the company. Remember they have 25% offtake rights. That is their prize. At $3.50 with what is looking like a 200Mt+ deposit, that appears to tick a lot of boxes in terms of pathway to production, with a mineral resource that appears to be in high demand for a decade or more and significant exploration upside, I wouldn't necessarily assume that $3.50 is overs.
If the SP sharply plunges may I suggest there will be one or two in the queue to buy below $3.50 going for the arbitrage.
I see the biggest risk to the $3.50 offer to be FIRB approval. If that doesn't go through the SP is no longer backstopped.