system
A chat on subreddit /r/wallstreetbets
human
Historical too just like any other stock and current change for each day

gpt
Write a script, run it every x minutes with cron. Every time it runs, it gets current stock price quotes from Alphavantage.co API (or wherever), calculates the new index value, inserts it into a database table, and tweets out if the delta is above 1% 
  
 A simple web app can be written to read the data in that table and return it as JSON. Graphs on the frontend can be done with plotly or something similar.