The original Famicom sold programs that allowed for the Trading of Japanese stocks through the phoneline

Starting in the mid 80s there were cartridges sold that allowed for the trading of Japanese stocks through a communication adapter that connected to the phone line and snapped into the Famicom

［あの大ヒット商品］は既に日本で作られていた！

I found some commercials for them

Nippon Securities Famicom Home Trade

https://youtu.be/3ZJDL6wglgA?si=VZ _nYFrDQN68QIZe

Nikko Securities Famicom Home Trade One

https://youtu.be/h6AngFFqw_w?si= C0uu4SR8WJHnHdGk

by UsuallyTheException