Mark Otto, director with trading firm Knight Capital Group Inc., weighs in on China's PMI data as well as its impact on global growth. China's manufacturing-activity growth has slowed in April, according to HSBC data released Tuesday. The preliminary or "flash" version of HSBC's manufacturing Purchasing Managers' Index fell to a two-month low of 50.5 from March's final reading of 51.6. Also on Tuesday, manufacturing output in Europe contracted for a 15th month in April as a composite index based on a survey of purchasing managers held at 46.5, London-based Markit Economics said today. Finally, the U.S. flash manufacturing purchasing managers index fell to a 52.0 reading in April from 54.6 in March, Markit said Tuesday, which is the lowest reading in six months.