How can I get the day's high price while the day is going on ? Say, it's 10:30 am and I want to know what is the highest price a stock has reached so far. How can I do that?
If you want to check just the high price in cash market look at api from yfinance or alphavatange. Sort by max "high" column on 1 min data and you'll have day high while day is in progress.
