Cost basis per share is a key financial concept that helps business owners determine the value of their investments. Put simply, it is the amount paid for each share of stock, including all costs associated with purchase, such as brokerage commissions and fees. Understanding cost basis per share is important if you plan to sell your stocks – if you don’t know the exact cost basis of each share, then you won’t be able to accurately calculate the gain (or loss) when you sell them. Knowing and properly tracking your cost basis per share can help you make informed decisions about your investments.