When it comes to securities investing, market liquidity refers to how easily you can buy or sell an investment at a fair market price when you want to. When a security is illiquid—meaning it has low market liquidity—finding a buyer when you want to sell might be difficult. You might have to accept a lower price if you need to sell quickly. In some cases, you might not be able to sell at all if no one is willing to buy at a price you’re willing to accept. If you want to buy an illiquid security, you might have to pay a higher price or wait longer to find a seller.