Investors should look at all of their accounts as a unified portfolio to construct a portfolio that is low cost, well diversified, and tax efficient. Those who are new to the concept are often overwhelmed by the complexity involved in maintaining such a portfolio. Using a spreadsheet to maintain a portfolio is intended to suggest one way of easing the burden.

Asset allocation

• Cells in the rows for Taxable, Roth IRA. and 401(k) should be manually entered. All other cells can be automatically calculated.
• Each cell in the Total row represents the total amount of domestic stocks. that of real estate investment trusts (REITs), and so on.
• The Desired row represents the desired amount of dollars in each asset class and can be calculated by multiplying the value of your portfolio by the percentages in your target asset allocation.
• The Difference row tells you how far off your portfolio is relative to your desired asset allocation. It can be calculated by subtracting a cell in the Total row from the corresponding cell in the Desired row.

Sample spreadsheets

• Here is a sample spreadsheet in this style. It includes the additional features above; it can also adjust for the different after-tax value of assets in different accounts, and combine multiple subclasses into one class (so that you may have a target allocation to foreign stocks, and separate targets for developed and emerging markets). A simpler version is also available; it does not track subclasses.
• One important aspect of of maintaining your asset allocation is to do periodic rebalancing. A sample rebalancing spreadsheet is available from Google Drive (by forum member LadyGeek). [1] Three example approaches are used, which could be incorporated into any of the sample spreadsheets.

Suggested improvements

• You might want to make a separate Target row to keep track of your target allocation; in that case, the Desired row would be the product of the Target row and the total portfolio.
• Similarly, you might make an Actual row to compute your percentage allocation, so that you could compare your target percentages to your actual percentages.
• If you have funds which cover multiple asset classes, you can put each fund in a different row, make an extra column for the total fund value, and have the spreadsheet automatically compute the amount of the fund which is in each class. This allows you to easily track the effect on your allocation of adding $10,000 to a balanced fund.

Asset allocation visualized

tfb’s article, Cascading Asset Allocation Method. describes how to select select a portfolio’s by visualizing the process as a top-down hierarchy. The most important selection is at the top (stocks/bonds), which then breaks down into smaller asset classes. Selection of the actual funds is done last, which is at the bottom of the chart. Two spreadsheets are available.

First, forum member pradador has created a spreadsheet which allows one to create a portfolio by following the advice in the article. The spreadsheet is available on Google Drive: Cascading Asset Allocation (The spreadsheet was further modified by forum member LadyGeek to include error checking.) [2]

This spreadsheet includes a fixed income major asset category, which is not mentioned in the article. There is no consensus on the role of fixed income in a portfolio; it’s dependent on your situation. If fixed income is considered as a bond, then set the percentage of Fixed Income to 0.

There are two tabs:

• Top Down: Starting on the left side and proceed to the right, enter the desired asset allocations to arrive at the percentage of each fund’s contribution to your portfolio. The bottom row is reserved for error checking. If an entry error is made (the percentages do not add up to 100%), an error will be displayed.
• Bottom Up: Use this tab to determine the asset allocation percentages of your portfolio when you know the funds. In the right-most column, enter the percentages and funds. The spreadsheet will work left and arrive at the asset allocations. The blank cell in the lower right-most corner will display an error if the percentage does not add up to 100%.

Forum member Ducks has another variation. The first page breaks down your asset allocation. The second page checks how close you are to your desired allocation and helps you figure out how to rebalance.

Track your portfolio in real-time

Spreadsheets by forum member swimirvine determine your asset allocation in a colorful way using real-time fund information. They also help with portfolio rebalancing. Be sure to align each fund with its associated asset class category across all of the account types, e.g. Large caps as the first entry should have a large cap fund as the first entry in all the account types.

• Google Sheets: swimirvine portfolio manager Copy this file to your Google Drive account; as it contains Google Finance functions which only work online from within Google. Google Finance functions limit real-time information to mutual funds ; for exchange-traded funds (ETFs) the expense ratios will have to be added manually.
• MS Excel: swimirvine portfolio manager.xlsm. The Yahoo! Groups EXCEL Stock Market Functions Add-in must be installed; subscribe to this group to download (access is immediate). Real-time expense ratios for ETFs and mutual funds are supported. [note 1]

How to use a proxy fund

Google Finance offers historical and real-time securities information using the GoogleFinance() function in Google Sheets.

If you have funds held in a Collective Investment Trust (CIT). in which there is no ticker symbol, then you can use a proxy fund to keep your balance roughly up to date using the GoogleFinance functions in Google spreadsheets. [note 2]

For example, suppose you hold the government’s Thrift Savings Plan C Fund, which is a collective investment trust (CIT) that tracks the S&P 500 index. Find out the closing price of the CIT on the current day, and also find a similar proxy fund, such as Vanguard’s institutional index fund (VINIX).

For example, suppose the C Fund’s closing price is $23.6602 and Vanguard’s VINIX is $167.75. This means that a share of the C Fund is worth 7.08 times a share of VINIX (167.75/23.6602).

To maintain a real-time estimate of your C Fund balance without needing to update the C Fund’s share price every day, you can instead take the daily price of VINIX and divide it by the multiplier to get an approximate share price for the C Fund.

For example, these could be the cell along a row in your spreadsheet and this is what you would enter into them.

Implementing a proxy fund