This new update - BlockStreet v2.4.0 - brings a new cool mechanic asked by the BlockStreet community:

Market Crashes & Company Bankruptcies
Under certain conditions, certain stocks may crash, and certain companies may become bankrupt (and worthless). Companies with higher risk are more subject to crashes and bankruptcies. Although enabled by default, this mechanism can be disabled through configuration.

• If a company is trading below a certain percentage of its original price, then, there is a certain probability (configurable) for the company's stocks to crash. This probability will be higher for companies with higher risk!
• Whenever the stocks of a company crash, the value of each stock will become 0 and the company will be marked as bankrupt.
• Players can still sell their stocks (although they'll be worthless) but can no longer buy stocks from a bankrupt company.
• Server administrators can use the command /invest delete [companyId] to delete the bankrupt company.

Hope you enjoy this new mechanic!
Happy Trading