Out of all those factors, sadly I believe #4 to have the most effect on the market. Although #1 is the force that drives the market, #4 has more sway than it should and for that reason I believe it has the biggest effect. You see people reacting to fake news even, because people can't be bothered to corroborate a story. Instead they act on a whim, and that is why the market acts irrationally from time to time.