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Cost basis equals the total cost to you of a security you purchased. It includes commissions, fees, and mutual fund loads. It also includes all purchases, even reinvestments of dividends and capital gains distributions. However, it excludes the cost of any shares you've sold or given away. Also, it is reduced in a return-of-capital transaction.
Notes
Quicken assumes, unless you tell it otherwise, that the shares you sell are the ones you've had the longest. You can tell Quicken which lots (or portions of lots) to sell when you enter a Sell transaction.
After you set up a Quicken investment account, Quicken keeps track of the cost basis of each security. It takes the dollar amount you enter for the first transaction involving a given security and uses this as the cost basis as of the date of the first transaction. Subsequent purchase costs are added to the cost basis; the cost of shares subsequently sold and any return of capital are subtracted from it.
To see your lots and cost basis at any time, open the Portfolio (choose Investing tab > View > Portfolio) and expand the security you want information about.
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