It doesn’t take much for sentiment to shift abruptly on Wall Street. Markets could be up one moment, then all of a sudden crash on account of a negative development. And looking at its current state, it won’t take much for it to come tumbling down, says Morgan Stanley’s chief investment officer and chief US equity strategist, Mike Wilson. “The S&P 500 risk/reward today is one of the worst I’ve ever seen, given the earnings setup that we see in front of us combined with the valuation that we have