LCYB didn't use nor want the NOL's. In order to use them, they'd have had to buy the business as a going concern and... (this is important, so pay attention)... take responsibility for the debt and other liabilities. They bought the assets only, and that is another of those clearly documented facts.
PWC got approval to do a KERP, but it had stipulations, namely that the secured creditors would have to be paid in full from a successful SISP in order for the KERP payments to be made. The SISP failed, no bids whatsoever, the secured creditors were only paid a fraction of the debt, so no KERP payments were made.
The stock tanked because the business lost money every year that BioAmber ran it, the more it ran, the more they lost. The price of the stock tanked, so no selling stock to cover the losses. The creditors weren't going to put more of their money into the pit. Takes cash to run a business, so they filed for bankruptcy.
The shares are forever yours, nobody wants them or needs them for anything. Why would they? They don't own anything, the company that issued them is gone, corporate charter revoked by Delaware, not even a company on paper anymore.
Ever wondered why nobody has heard even a whisper from BioAmber, Inc., since the board resigned nearly 6 years ago?