** Shares of Huntington Ingalls HII.N down 9.3% at $329.10, hitting their lowest level in more than four months

** Shipbuilder posts lower Q1 operating margin, hurt by higher costs, even as revenue beat Wall Street estimates

** Q1 operating margin falls to 5% from 5.9% a year ago, with cost of product sales up 20%; co's key Newport News shipbuilding segment's margin also declines despite higher sales

** HII said higher costs amid inflation and global trade volatility weighed on results, despite strong demand for its vessels

** HII shares down 3% YTD, compared with the S&P 500's .SPX 5.9% rise

** 12 analysts on average rate the stock "buy", with a median price target of $419 - LSEG-compiled data