TurboTax certainly does allow you to enter security sales where you have not received a 1099-B, though it sounds like this was a "same day" sale of employer stock. In this situation you don't have to report the sale though you may wish to report the sale to take advantage of the small loss that typically occurs in this situation.
In the desktop product you start the "Stocks, Mutual Funds, Bonds, Other" interview, tell TurboTax that you had security sales, and then tell TurboTax that you did not receive a 1099-B. That places you in a somewhat different interview than if you reply "Yes" to the 1099-B? question. I assume the online product does something similar.
The alternative interview also has "guided" interview for all sorts of sales, including sales of employee stock but there's no "Income Tax Return Reporting Requirement" that means you must use the guided interview. All security sales that show up on Form 8949 look exactly the sale:
There's nothing there that says "This was employer stock that I sold." So simply enter the five pieces of information that's needed to report the sale, and you're done.
Thanks for the quick reply TomYoung. It was not a same day sale/cashless exercise-- the stock was exercised months prior to the sale-- so I believe I'm required to report. I am using the online product, and if I choose the "Stocks, Bonds, Other" interview, it does not ask a "did you receive a 1099-B" question--all questions after assume I have a 1099-B form. Further, if I choose the "Other" alternative interview, in the drop down menu for "What type of investment did you sell?" the only stock option is "stock (non-employee)". So it seems the online product assumes that all employee stock sales produce 1099-B forms, but the desktop product does not. Regardless, I'll simply use the alternative interview path as you suggest. This is helpful clarity, much appreciated.
"It was not a same day sale/cashless exercise"
Since it wasn't a same day sale then you certainly should have received a 1099-B in almost most situations. Was the stock not sold through an broker, maybe sold back to the employer, perhaps?