PTT, MCC, LCY, LCYB, et al, are all still in business, making chemicals and products from those chemicals. The deals they make between themselves are irrelevant to this discussion.
Meanwhile, BioAmber went out of business over 5 years ago when it was liquidated and shut down. The board and executives resigned when the liquidation bid from LCYB was accepted, then later approved by the courts in Canada and the US, closed in October of 2018. All other employees were laid off, either after operations were ceased and the plant laid up (prior to liquidation) or after the remaining sales of finished product, tools, and parts were completed.
The ticker was deleted by FINRA in November of 2019 (over 4 years ago) after the US court closed the proceedings. The state of Delaware later voided the company charter for failure to file required reports and pay taxes (likely $500k owed when the charter was voided).
There is no ticker, no transfer agent, not even a company on paper anymore, the company that issued the stock is gone.
LCYB bought all of the assets, including the plant and the patents and other IP. Nobody needed or ever even mentioned buying the stock. Why would they? And, apparently, the product isn't the gold mine it is purported to be, since LCYB announced they'd be making other products at the plant.
Does it bother you that the company hasn't said a single word since the executives and board resigned in August of 2018?