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Dunder Data Challenge #4 - Finding the Date of the Largest Percentage Stock Price Drop

dunder data challenges Nov 12, 2019

In this challenge, you are given a table of closing stock prices for 10 different stocks with data going back as far as 1999. For each stock, find the date where it had its largest one-day percentage loss.

Begin working this challenge now in a Jupyter Notebook with Binder

Begin working this challenge now in a Jupyter Notebook thanks to Binder ( The data is found in the stocks10.csv file with the ticker symbol as a column name. The Dunder Data Challenges Github repository also contains all of the challenges.


Can you return a Series that has the ticker symbols in the index and the date where the largest percentage price drop happened as the values? There is a nice, fast solution that uses just a minimal amount of code without any loops.

Extra challenge

Can you return a DataFrame with the ticker symbol as the columns with a row for the date and another row for the percentage price drop?

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