The Iowa Electronic Markets
The Capital Asset Pricing
Curriculum using the IEM
Prepared for the Fall 1999 IEM*IDEA/FIPSE Conference
By Thomas A. Rietz
The Capital Asset Pricing Model
Apply the CAPM to determine expected stock returns
Students should be able to:
1. Find betas for stocks
2. Understand and compute betas for stocks
3. Determine appropriate risk free rates and market risk premiums
4. Apply the CAPM to determine expected asset returns
Evaluate actual stock performance
Students should be able to:
1. Determine actual stock returns over specified periods
2. Compare actual returns to CAPM required returns to evaluate performance
Implement investment /trading strategies
Based on sound financial analysis, students should be able to turn expectations into actions.
Important Aspects of the Assignment
Students replicate analysis from the lecture.
Students start with specific directed tasks and slowly forces students to expand and generalize
Students build on previous knowledge and experience.
The Capital Asset Pricing Model (CAPM)
2. The Feasible Set and Efficient Frontier
3. Investor Utility Maximization
4. The CAPM Asset Pricing Equation
5. Applying the CAPM
6. Notes on Estimating Betas
Introduction to the IEM
The Iowa Electronic Market (IEM for short) is a computerized market on which financial contracts can
be traded (bought or sold). For this assignment, we will be using a series of contracts based on three
popular companies, Apple Computers (AAPL), IBM (IBM) and Microsoft (MSFT), and an important
index called the S&P500 index. Shares of the firms trade over the counter (NASDAQ) and on the New
York Stock Exchange (NYSE). Similarly, a daily index value is determined for the S&P500 based upon
the stock prices of the 500 companies that compose of it.
The contracts we will use are based on the shares of Apple computers, IBM and Microsoft, and on the
value of the S&P500. These contracts are listed on the IEM under the market label “Computer Industry
Returns Market” or “Comp_Ret” for short. These contracts are described briefly later in this note and in
more depth in the IEM Trader‟s Manual. Detailed descriptions of these markets are available at the IEM
The objectives of the IEM assignments are to help you apply class concepts in a "real world,"
unstructured way to learn how to:
1. Apply the CAPM to determine expected stock returns
2. Evaluate actual stock performance
3. Implement investment /trading strategies
Opening an IEM Account
All students need to open an account with the Iowa Electronic Market. This involves a minimum deposit
of ____ dollars. Funds remaining in your account are refundable at the end of the semester.
You can open an IEM account over the internet. To do so, go to the sign-up webpage:
and follow the instructions given to you by your instructor. (DO NOT use forms other than those given
to you by your instructor. Using other forms may result in fees or decreased deposits in your account.)
After filling out your signup forms, you may need to deposit cash with the IEM office (W283 PBAB,
phone 335-0881). Your instructor will give you details about any deposits you need to make.
Accessing the IEM
You can access the IEM through its website address:
The IEM market has several contracts trading under it. The contracts of interest for our course are the
Computer Industry Returns Market (Comp_Ret, for short).
You access your trading account from the market pages or directly at:
Computer Industry Returns Contracts
The Computer Industry Returns Contracts consist of a series of contracts. Every month, existing
contracts in the series are liquidated and payments are made as described below. Then, new
contracts are created as described below. These events occur on the Monday after the exchange-
traded options for the underlying stocks expire (the Monday after the third Friday of each month).
The liquidation values for the contracts in this market are determined solely by the rates of return of
Apple Computers Common Stock (AAPL), IBM Common Stock (IBM), Microsoft Common Stock
(MSFT) and the S&P500 index (SP500). Whichever of these has the highest rate of return as specified
below will payoff $1.00 per share. The remaining contracts will payoff zero. Thus, to do well in this
market, you will need to understand what determines real stock market returns.
Contracts will be designated by a ticker symbol and a letter denoting the month of contract liquidation.
Thus, the contracts traded in this market for liquidation in month “m” are:
Code Underlying Asset Liquidation Value
AAPLm Apple Computers $1.00 if AAPL Return Highest
IBMm IBM $1.00 if IBM Return Highest
MSFTm Microsoft $1.00 if MSFT Return Highest
SP500m S&P 500 Market Index $1.00 if SP500 Return Highest
In these contract codes, “m” refers to the month of expiration as given by the following table:
Month Designation Month Designation Month Designation
January a May e September i
February b June f October j
March c July g November k
April d August h December l
For AAPLm, IBMm and MSFTm, the dividend-adjusted rate of return is computed based on closing
stock prices of the underlying listed firm between the third Friday in the liquidation month and the third
Friday in the previous month. For these purposes, closing prices as reported in the Midwest edition of
the Wall Street Journal are used. In particular, this return is calculated as follows. First, the raw return
on the underlying stock is computed (as the closing price on the third Friday of the liquidation month,
minus the closing price from the third Friday of the previous month, plus any dividends on ex-dividend
dates). Then, we divide the raw return by the closing stock price from the previous month to arrive at
the dividend-adjusted rate of return.
For the SP500 contract, the return is computed as the capital gains rate of return. To do this, subtract
the closing index value on the third Friday of the previous month from the closing index value on the
third Friday of the liquidation month. Then, divide by the previous month‟s closing index value.
Trading on the IEM
You can trade on the IEM in several ways. First, you can buy or sell unit portfolios. A unit portfolio is a
set of contracts such as AAPLm, IBMm, MSFTm and SP500m. You can always buy or sell such
portfolios for $1.00 each. Thus, when you start to trade and do not own any contracts, you can buy a
unit portfolio and then start to trade. (To do this, select the appropriate contract under “Buy Bundles” or
“Sell Bundles” in the “Market Order” drop down menu. Enter a quantity and press the “Market Order”
Second, you can buy or sell using a "market order." On the market screen, you will see that some
individuals have posted an order to buy or to sell a contract (e.g., MSFTi, the contract for September
liquidation in the Computer Industry Returns Market) at a specific price. If you believe that a posted
order represents a good deal, you can buy or sell at the posted price. (To do this, select the
appropriate contract under “Buy at Best Ask” or “Sell at Best Bid” in the “Market Order” drop down
menu. Enter a quantity and press the “Market Order” button.)
Third, you can buy or sell using a "limit order." To do so, you state the price at which you are willing to
buy or sell a contract and post a limit order on the screen. In doing so, you are waiting for someone
who is willing to buy or sell at your stated price. In this manner, when your order executes, it will
execute at your stated price, not at somebody else‟s. The negative is that the order may never execute
because nobody likes your price because it is too high or low. (To place a limit order, select the
appropriate contract under “Post a Bid” or “Post an Ask” in the “Limit Order” drop down menu. Enter a
price, quantity and expiration date and press the “Limit Order” button.)
Completing Your Assignments and Submitting Them
As you can see below, the IEM assignments are extensive, multi-part assignments that draw together
many concepts from the class. It would be wise to work on the various parts of the assignments as we
go over the relevant topics in class. To prepare the assignments for submission, please use the
1. Each assignment must be typed. Label clearly each assignment with a cover page giving
your name, student number, and section number.
2. Complete each part in a separate section clearly labeling them Part 1, Part 2, etc.
3. Within each section, give the requested information, including sources of information
gathered and equations used to calculate results.
4. Turn in your completed assignment to your instructor on the date it is due.
Part 1: Finding and Computing Returns DUE: ___________
In this part of the assignment, you will learn where to find current and historical prices and how to
Current stock returns
The IEM Computer Industry Returns or MSFT (Microsoft) Price Level markets depend upon the
following three stocks: AAPL, IBM, MSFT and the S&P500 index. The prices of these stocks and the
value of the S&P500 index are reported in the Wall Street Journal and in various places on-line (e.g.,
Starting on the third Friday of ____________, record the closing prices each Friday for AAPL, IBM,
MSFT and the S&P500 index. (If you use a print source such as the Wall Street Journal, notice that,
typically, these prices will appear in the following Monday‟s edition.) Continue recording prices each
Friday through the third Friday in ________. Also, find out if any dividends are paid on the three stocks
AAPL, IBM and MSFT during any week. Report this information in a table labeled Table 1. (Note:
While you are free to use any source, the contracts are liquidated based on Wall Street Journal
For each Friday from ________ to ________, report the dividend adjusted return from the first recorded
date to the current date for each stock calculated from the prices and dividends (if any) in Table 1.
Report these returns in Table 1 as well.
Historical stock returns
Download the third Friday to third Friday stock returns for AAPL, IBM, MSFT, the S&P500 and one-
month Treasury Bills from the IEM website at:
You will use these returns in later parts of this exercise.
Download 5 years worth of monthly stock prices and dividends from Yahoo's website as follows.
1. Go to : http://quote.yahoo.com
2. Enter AAPL as the ticker symbol and press the "get quote" button.
3. Select the "Chart" link.
4. At the bottom of the chart, select the "monthly" tables link.
5. Select the appropriate dates in the resulting table and press the "get historical data" button
with the "Monthly" radio button selected.
6. At the bottom of the table, select the "download spreadsheet format" link.
7. Save the resulting "csv" format file. You can load this into Excel for analysis.
8. Select the "Dividend" radio button and press the "get historical data" button again to
Repeat this procedure for AAPL, IBM, MSFT and the S&P500 (ticker symbol ^spx). You can also
download 3 month T-Bill rates using the ticker symbol "^irx". The T-Bill data is in the form of return
For each stock, each month, use Excel to compute the dividend adjusted return. Also, compute the
return to the S&P500. Save this data for use later.
Returns to IEM Contracts
Make at least one trade in the IEM Computer Industry Returns market between the ________ and
________. Choose one trade to use for the rest of this part.
Report the date of the trade, the contract traded and the price. Attach a print out showing your trading
activity. (You can either submit a “Processed Orders” report or an „Order History” report. To get the
first report, make sure that the “confirm” box is checked on the trading screen. You will be asked to
“execute” the order. Upon execution, the “Processed Orders” report will appear. To get the second
report, go to “My Account” information select “view order history” and print the resulting report.)
Based on the date of your trade, what is the holding periods (in days) to the contract buyer if each
contract is held to its liquidation date?
Calculate and report the return over this holding period to the contract buyer if the contract liquidates for
Also calculate and report the return over the holding period to the contract buyer if the contract
liquidates for $0.
Part 2: Computing Betas DUE: ___________
In this part of the assignment, you will learn how to analyze stock returns. You will look at historical
averages, standard deviations and correlations. You will learn how to find betas on line and how to
compute your own betas for stocks.
Historical Analysis of IEM Returns
Use the monthly IEM returns downloaded in part one for this part of the assignment. Analyze these
returns by reporting the following information (all numbers can be computed in Excel):
1. Report the historical average monthly return for each stock, the S&P500 index and T-Bills.
(Use the Excel "average" function.)
2. Report the historical standard deviation in monthly returns for each stock, the S&P500 and T-
Bills. (Use the Excel "stdev" function.)
3. Report the correlation coefficient between monthly returns for each stock and T-bills with the
S&P500. (Use the Excel "correl" function.) These correlation coefficients will be the raw betas
for the stocks computed from the "characteristic line" as discussed in class.
4. Compute and report the adjusted betas from the correlation coefficients computed above.
(adjusted = 1/3 + 2/3xraw.)
Historical Analysis of Yahoo Returns
Repeat the analysis above using the five years of monthly returns collected from Yahoo in Part 1.
Looking up Betas
Look up betas for each stock on Yahoo using the following procedure:
1. Go to : http://quote.yahoo.com
2. Enter AAPL as the ticker symbol and press the "get quote" button.
3. Select the "Profile" link.
4. Page down to "Statistics at a Glance"
5. These statistics include "beta."
Repeat this exercise for each stock.
Compare and contrasts the betas you get from each method. How close are they? Why are they
different? How stable are the betas? Given the information you have, do you think that beta's are a
stable enough measure to use for the CAPM?
Part 3: Applying the CAPM DUE: ___________
In this part of the assignment, you will learn how to apply the CAPM to compute expected returns. You
will have to make decisions about the risk free rate, the market risk premium and the appropriate betas.
Finding Risk Free Rates
Current risk free rates can be found online at various websites. The current 1 month treasury rate can
be found on the IEM at the website:
You can also get risk free rates from Yahoo. The ticker symbol for 3 month T-bills is ^inx, 5 year notes
is ^fvx, 10 year notes is ^tnx and 30 year bonds is ^tyx.
Determining the market risk premium
Using the date from Part 1, subtract the monthly T-Bill rate from the S&P500 return. This is the monthly
market risk premium. What is the average monthly risk premium according to your IEM data?
Computing the Expected Return from the CAPM
Using the current monthly T-Bill rate from the IEM and the average monthly risk premium calculated
from IEM data above, compute the one-month expected return for each of the three stocks and the
S&P500 index using:
1. Betas you calculated from IEM data in Part 2.
2. Betas you calculated from Yahoo data in Part 2.
3. Betas you looked up on Yahoo in part 2.
What risk free rate do you think should be used in the CAPM? Does the time horizon (from 1-month T-
bill rates to 30-year T-Bond rates) matter? What seems most appropriate to you?
Do you think that the risk premium used is an adequate measure of the risk premium? Can you find
other sources for the risk premium from your book, course materials or the web?
What are the differences between the expected returns computed using the various betas above?
How stable are these returns? Can you order the stocks from highest expected return to lowest? Does
the source of the beta matter?
Part 4: Evaluating Securities DUE: ___________
In this part of the assignment, you will learn how to use the CAPM to evaluate the historical
performance of assets.
Recall the average historical returns from Part 1 of the assignment.
Recall the CAPM predicted returns from Part 3 of the assignment.
Subtract the CAPM predicted return from the historical average return of the stock. This is the amount
by which the stock outperformed (+) or underperformed (-) the required return as predicted by CAPM
over the historical time period. This is known at the stocks "alpha."
Graph the Security Market Line (relationship between beta and the expected return) using the one-
month risk free rate and the risk premium from the IEM used in Part 3. On this graph, also graph the
average monthly return (from part 1) and beta (from part 2) for each of the three stocks. The distance
that the stock lies above the Security Market Line is also the stocks "alpha."
According to the stocks' alphas, which stocks outperformed or underperformed historically? Can you
rank order their performance?
Can you explain why each stock either outperformed or underperformed? Were there special
circumstances for any of the companies? Do you think the historical performance will continue? Do
you think any of the companies face special circumstances now that will enable them to outperform in
the future? Are there any special circumstances that would cause them to underperform?
Part 5: Implications and Actions DUE: ___________
In this part of the assignment, you will use the CAPM to forecast returns for stocks and turn those
forecasts into actions on the IEM.
Given all of your analysis in parts 1 to 4, predict what each stock's return and the SP&500 return will be
for the next month. Justify these predictions using the analysis techniques developed in class and in
Which of the stocks do you predict will have the highest return? How confident are you of your
Given your predictions above, which IEM contract (AAPLm, IBMm, MSFTm or SP500m) should be
priced the highest at the beginning of trading during the current trading month. Justify your prediction.
(Recall that the contract with the highest actual monthly return will liquidate at $1. The others will expire
worthless. Thus, you need to predict which stock will have the highest monthly return in order to
determine which IEM contract will have the greatest likelihood of payoff. This contract should be priced
Actual IEM Prices
For each Friday that you report stock prices in Part 1, report the corresponding closing contract prices
on the IEM Computer Industry Returns and Microsoft Price Level markets in a table labeled Table 2.
(To access this information, use the “Market Info” button, select the market and select the “Price
History” report. Alternatively, you can access a price history by selecting the “History” link on the
market‟s webpage under the IEM address: http://www.biz.uiowa.edu/iem.)
Compare your prediction to the actual price of the contracts at the beginning of trade in the current
month. Can you reconcile your predictions with actual prices?
Note how prices evolve through time and correlate IEM price changes with the returns to date for the
stocks from Part 1.
Make at least one additional trade in the IEM Computer Industry Returns market between the
________ and ________. Log your trades. For each trade, report the date of the trade, the contract
traded and the prices. Attach a print out showing your trading activity. (You can either submit a
“Processed Orders” report or an „Order History” report. To get the first report, make sure that the
“confirm” box is checked on the trading screen. You will be asked to “execute” the order. Upon
execution, the “Processed Orders” report will appear. To get the second report, go to “My Account”
information select “view order history” and print the resulting report.)
Justify each trade you make using:
1. Your forecast returns
2. The actual returns do date
3. IEM prices at that time and
4. Any other information and analysis you wish to include.