The name of your controller class (.cs file) is CompaniesController.cs
.
That's a convention (default behavior) where MVC will automatically identify it as a controller.
When referencing this controller in your view, use Companies
only.
If you use CompaniesController
MVC will try to find a CS file named CompaniesControllerController
.
Correct code:
@using (Html.BeginForm("bgcTest", "Companies"))