uses a module to structure controller code

app/controllers/budgets/budgets_controller.rb

@@ -0,0 +1,9 @@
+module Budgets
+  class BudgetsController < ApplicationController
+    skip_authorization_check
+
+    def index
+    end
+
+  end
+end

app/controllers/budgets/investments_controller.rb

@@ -1,4 +1,4 @@
-class Budget
+module Budgets
   class InvestmentsController < ApplicationController
     skip_authorization_check
 

app/views/budgets/budgets/index.html.erb

@@ -0,0 +1 @@
+budgets index

config/routes.rb

@@ -75,8 +75,10 @@ Rails.application.routes.draw do
     end
   end
 
-  namespace :budget do
-    resources :investments, only: [:index]
+  scope module: :budgets do
+    resources :budgets do
+      resources :investments, only: [:index]
+    end
   end
 
   resources :stats, only: [:index]