Itās not possible for the value to be negative: that would mean you owe them money, which doesnāt make sense.
See the Debenhams - DEB.L thread for what can happen when a company goes bankrupt. But regardless of the specifics, if the company never makes money again (eg. because it ceases to exist), then your investment becomes more or less worthless because:
- If you still had the ability to sell your shares, no one would want to buy them at any price
- The company can no longer give you dividends
- If the companyās assets are sold off, you still might not get any of that money because sale proceeds will cover loan debt first, and shareholders last