3% stock market movements set in motion by the US president alone. "Great" insider trading potential. Have someone set up the right derivatives strategy and bam: instant millions.

I couldn't convince myself to immediately write that idea off as utter nonsense.

Anyone with more relevant financial experience? Can you reassure me this would be difficult to pull off? Or would you have to confirm this would be difficult to catch?

EDIT: Let me try put this in an even more neutral way. Let's say one knew down to the minute when the entire US and EU stock markets were going to sustain substantial losses. How much value one could siphon off without triggering too much suspicion? Surely market depth and trade volume must offer at least order of magnitude hints about that?