Running a live strategy over multiple instruments

[fiddy]

Is it possible to run a strategy over a list of instruments / multiple instruments when live trading.

[NinjaTrader_Bertrand]

Yes fiddy, in the Control Center > Strategies tab you can set up scripts that would run on a predefined instrument list for example, just right click in there and select New Strategy and then point to your list under the DataSeries section for it. The lists could be setup / customized in the Instrument Manager under the Tools menu.

[fiddy]

Can this be done in a simulated account to see the execution in real time etc

[StockFundoo]

Yes, running in simulated environment is a great way to test your stuff, before placing any real money online.
One can use either market replay to test the strategy or if your broker allows a Sim/paper account, you can connect to that and test your strategy live with paper money.