Delisted stocks refer to the stocks that are taken off from the exchanges. Delisted stocks have to be traded outside exchanges and in the over-the-counter market. A stock may get delisted due to multiple reasons, including bankruptcy, inadequate market capitalisation or failure to meet regulatory requirements.
Companies may delist voluntarily due to non-performance, amalgamations and mergers.
When a stock is being delisted, the promoters must offer to buy back the shares through a reverse book-building process.