Listed Securities are shares and other securities traded through an exchange like BSE, NSE, etc.
Every time a company goes public to offer their shares, they have to choose a listing exchange. The company has to meet the exchange requirements and pay the entry and yearly listing fees.
The listing requirements for these exchanges and platforms are stringent, and some companies don’t fulfill them.
The companies that don’t get listed on any trading platform are traded through the over-the-counter (OTC) market are called Unlisted Securities.