JPMorgan analyst Stephen Tusa downgraded Rockwell Automation (ROK) to Underweight from Neutral with a price target of $150, down from $151. The analyst says his checks with the company suggest the Street has "baked in too much optimism" with regards to Rockwell's Q1 estimates. Further, Tusa views Rockwell as the name most exposed to a slowing in PMI momentum. Early cycle discrete markets like auto are "typically the first to fade in this type of an environment," Tusa tells investors in a research note. The analyst this morning also upgraded 3M (MMM) to Neutral.