Return of capital (ROC) is a payment, or return, received from an investment that is not considered a taxable event and is not taxed as income. Market capitalization represents the total market value of a company's outstanding shares of stock.The basis of stocks or bonds you own generally is the purchase price plus the costs of purchase, such as commissions and recording or transfer fees. Each time you sell an investment in your taxable brokerage account, there's the potential to create income from a capital gain. Capital gains and cost basis. Learn how stock prices are determined for a company in the U.S. stock market, and check out a few examples of share price valuations. If you sell a stock for less than its original purchase price, your investment incurs a capital loss. Contents: Do you know the tax implications of your equity ownership? How supply and demand work in the stock market. Supply and demand determine the amounts of bids and asks.