And apparently chart-decreasing is blue, again opposite correlation to use in traffic lights, meaning "go"
I don't see it necessary to make a correlation to a stop-light's color coding. You could also argue why anything hot is colored red while cool is supposedly blue.
But it is something we humans do, particularly with signaling devices (which a chart is a form of too, arguably) you will see color used in similar fashions to convey a similar meaning. Red is internationally a STOP color, a danger, warning color, and used as such most everywhere; except the Japanese stock market apparently. Which is fine, just curious to me.
Another comment here said that in the US some traders flip their colors to indicate red=sell, green=buy, which makes more sense to me in terms of Japan.
Something I find entertaining about the stock colors is that the idioms "in the red" and "in the black" mean the same thing in Japanese as in English.