At one point, Noble Group was among the largest commodity trading firms in the world. During 2015-2019, the company was accused of accounting fraud, reported huge losses, and was facing insolvency and bankruptcy. The company was delisted from the Singapore Exchange, underwent debt restructuring to avoid bankruptcy, and now operates as a private company.
On the US OTC stock market, Noble Group's shares are still being traded in the form of ADRs (NOBGY) and F shares (NOBGF). Its shares are classified under the OTC Markets' "Pink Current Information" category.
How can the ADR and F shares of such a company continue to trade on the US OTC stock market even after the company was delisted and privatized?