Performance and Transactions

Anatomy of a portfolio

Every portfolio is composed of transactions each of which reference securities, of which are represented by a Ticker Symbol. This is what you see in the Overview, Fundamentals, and Performance views. The symbol for a security may represent a company's Common Stock, such as GOOG for Google. Or it may represent different classes of shares of a company's common stock, such as BRK.A and BRK.B for Berkshire Hathaway, or an Exchange-TradedFund, Mutual fund, or anything else that you can own shares of. Technically, a portfolio can contain a stock Index like the Dow (.DJI) or NASDAQ (.IXIC), but that is just a convenience so you can compare your securities' performance against the broader market; we will not discuss stock indexes further. We start with the fundamental unit of portfolios, the transaction.


A transaction is assumed to have the following values that you can set:

Share count: the number of shares referenced by the transaction. This can be zero for a "watchlist" item, that is, a stock that you added to your portfolio just to keep an eye on its performance, not because you own any shares of it.

Cost per share: the cost to purchase each share, in the currency of the exchange on which the share is traded. In the case of cash deposits or withdrawals, this is just the amount of the transaction.

Commission: the cost to execute the transaction with a broker

Type: One of "Buy", "Sell", "Sell Short", "Buy to Cover", "Deposit cash", "Withdraw cash", "Dividend", or "Split". Dividends and splits are computed automatically based on the traded company's history; you cannot set these yourself.

Share count, cost per share, and commission are all optional. If you leave any blank, we treat it as zero.

A transaction also has certain values that are set automatically based on its traded company:

Share price: the trading price of the share at the time computations are performed, in the currency of the company's stock exchange

Price change: the percentage change in the trading price of the share since the market open

Dividend value: For dividend transactions, this is the amount of the dividend per share of the stock

Finally, there are values that are derived from those we have looked at already:

Transaction-adjusted share count: this is the number of shares in the transaction, as of the time of the computation, based on the company's split history. For example, if you purchased 100 shares of a stock that then split 2:1 (meaning that you receive two shares in exchange for every individual share you own), this value would be 200.

Event-adjusted share count: this is like the transaction-adjusted share count, but instead of being split-adjusted to the present, it is adjusted to the time of a relevant event, such as a split or dividend issue.

Cash value: this value depends on the type of the transaction you decide to do. See Transaction types:

  • "Buy" or "Buy to Cover": The amount it cost to make the transaction. This is negative, since purchasing depletes your bank account. cash value = -(share count * cost per share + commission)

  • "Sell" or "Sell Short": The amount you made on the sale. cash value = share count * cost per share - commission

  • "Deposit cash": cash value = cost per share

  • "Withdraw cash": cash value = -cost per share

  • Dividend: cash value = event-adjusted share count * dividend value

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