** Shares in Rheinmetall RHMG.DE down around 8%, on track for their worst day in 4 years, after JPMorgan cut its rating to "neutral" from "overweight"

** Broker says German defence group missed consensus four times in the last six months, raising concerns over its performance in coming quarters

** Some investors have started to question whether the co is trying to do "too much too quickly", the broker notes

** Some of the proposed joint ventures, such as one with Lockheed Martin LMT.N, have taken longer than expected to finalise, which could lead to the co missing its sales forecast, the broker says

** "Whilst we do not fully share these concerns, investors are de-rating the shares and we are not sure this trend will reverse in the near term," it adds

** The push into naval shipbuilding is a high-risk/high-reward strategy, as the co appears willing to take on fixed price contracts in the hope of much better margins, it says

** The stock is at the bottom of European blue-chip index STOXX 50 .STOXX50