You are correct in that TurboTax does indeed have a 10-Million dollar (actually $9,999,999) limit in the data entry field for Schedule D (capital gains and losses). That said, you can still use TurboTax when the dollar amounts are higher than this, as the program will accurately add together sums totaling at least up to 8-figures, which is more than enough to cover the 50-million dollars in gross sales proceeds reported on your Form 1099-B. So, your answer is genuinely yes, you can still use TurboTax to file your tax return.
The key, you see, to get the program to allow data entries that in total are 10-million or higher is the "break them up" into a series of somewhat smaller transactions, such that each individual group of securities sales don't total more than 10-million dollars. In your case, it seems that you'd need at least (6) different securities groupings, such that when totaled together, they will equal between 50-million and 60-million.
Perhaps a visual example will help illustrate this principle. Please see the (2) screen capture images below (simply click the pictures to open), created in TurboTax Premier desktop, for an illustration of how (2) groupings of securities have been aggregated together to total just under 20-million dollars in gross sales proceeds. Combining even larger amounts, such as what you have, can be done using the very same methodology.
The TurboTax program will accept this without returning any errors in the software And while it will require doing some math on your part, to enter your 50-million in brokerage data this way, by dividing up your 1099-B into several large blocks of securities (assuming you don't want to enter all 600 individual trades, which is also an option, albeit a tedious one), such a tax return can in fact be completed in TurboTax.
Thank you for asking this question, and good luck with your trading activities.
