Get your taxes done using TurboTax

TurboTax won't take a proceeds on one transaction over 9.999.999

but it will take a total proceeds over 9,999,999 on the summary of proceeds for a Sales Category.

Go figure.

If you have one stock with proceeds over 9,999,999 as you say,

delete it and divide the amounts by 3.0

then enter the stock details three times.