That's what's called business ability.
It's like fishing.

Any old fisherman can judge in half an hour whether the fish are going to bite all day or not.

If he's wrong once, he'll be right a hundred times.

Well, I felt talking was no good, and so did Bamberger, and the shares began to go down before the storm.

If the big slump had come there'd have been a heap of money lost.