JPMorgan analyst Tycho Peterson downgraded Luminex to Underweight from Neutral and lowered his price target for the shares to $21 from $23. While the company's results year-to-date have been generally in line, its margins have been pressured by the acquired flow cytometry business and a growing mix of the MDx portfolio, Peterson tells investors in a research note. Further, he believes Luminex's execution on new product launches "remains a show-me story" in light of intensifying competition, especially in the MDx market. The analyst views the stock as fully valued and sees better risk/reward opportunities elsewhere.