On October 24, 1929, a record 12.9 million shares of the stock were traded on a day that became better known as "."

The black thursday of the Wall Street Crash of 1929.

Explanation:

As the exercise presents, on October 24 of 1929, a record of 12.9 million shares of the stock were traded on a day that became better known as the black thursday. On that day's opening only, the market lost 11 percent of its value at the opening bell. This was the start of what we now know as the Wall Street Crash of 1929.  

we need the diagram to answer this correctly.