Fetch data from different form on user input

Fetch data from different form on user input

Hi, I'm trying to do something simple (I think) but can't quite figure out the Deluge syntax after researching topics on fetching data.
 
Form A is a "source" table for investments, including these fields:
Symbol
Price

Form B is for entering stock positions, including these fields:
Security (which is a lookup field for Symbol in Form A)
Current_Price

In Form B, when I select a Security, I'd like the Current_Price to populate with the matching Price for that Symbol from Form A.

Any help is greatly appreciated.

Thanks!
Marv