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发表于 2012-4-3 11:05
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Gary Zeller, an independent portfolio manager who manages money for high-net-worth individuals, is a proponent of the efficient market hypothesis. He uses the Treynor-Black model to determine asset allocations for his portfolios. At the moment, he is considering several investments for new portfolios. Here are their characteristics.Stock Expected | 12-Month Return
Five-Year Avg. | Standard
Deviation | Beta | Hearthstone [td=1,1,120]15% | 34% | 1.6 | Imperial Shipyards | 9% | 12% | 0.7 | Minster Mask and Costume | 26% | 44% | 1.4 | Kustom Auto | 11% | 14% | 0.85 |
The risk-free rate is 5.7%. The expected return of the S&P 500 Index is 10%, and the index’s standard deviation is 14%.
Zeller plans to create a portfolio using a mix of the S&P 500 Index, the risk-free asset, and the four stocks discussed above. He uses the data above to select the appropriate asset allocations to maximize returns.
Recent market activity has Zeller concerned. For several weeks he has seen stocks with weak fundamentals stage a strong rally, while solid, steady-growth stocks have lagged. After extensive research into technical trends and an analysis of the market’s fundamentals, Zeller has come to believe the recent trend in the market is likely to continue, with speculative stocks continuing to rally.
Despite the gains in speculative stocks, Zeller sees continued weakness in larger, solid stocks causing a decline in the S&P 500 Index. To compensate for this risk, he purchases put options on the 50 largest stocks in the capitalization-weighted index instead of buying the index itself for the new portfolios.
Later that day, Zeller receives an e-mail from Florence Whitaker, a client whose portfolio has performed poorly in recent months. She is not happy with the results and questions Zeller’s allocation strategy.
In a response e-mail, Zeller defends the Treynor-Black model and makes the following points:- The strategy is designed to beat the market, but not necessarily to generate gains when the market is down.
- In your portfolio, I overweight the stocks with the highest potential return to boost performance.
- A mix of individual stocks and index funds gives the portfolio better potential returns than the index, while offering less risk than the individual stocks.
- All of the stocks in your portfolio have betas below 1.
After sending the e-mail, Zeller opens up a spreadsheet to crunch some numbers. Several of his portfolios have underperformed over the last year, and he resolves to consider whether he should relax his assumptions about the accuracy of forecasts.From highest allocation to lowest, how should Zeller allocate the four stocks in his portfolio? A)
| Hearthstone, Minster Mask and Costume, Kustom Auto, Imperial Shipyards. |
| B)
| Minster Mask and Costume, Kustom Auto, Imperial Shipyards, Hearthstone. |
| C)
| Minster Mask and Costume, Hearthstone, Kustom Auto, Imperial Shipyards. |
|
The Treynor-Black model calls for greater weights to stocks with high forecast alpha relative to unsystematic risk. The Sharpe ratio reflects that relationship. To calculate the Sharpe ratio, we subtract the risk free rate from the expected stock returns, and then divide by the stock’s standard deviation. Beta is not a measure of unsystematic risk, so it should not be used. Sharpe ratios for the four stocks are as follows:Hearthstone = 27.35%.
Imperial = 27.50%.
Kustom Auto = 37.86%.
Minster = 46.14%.
The higher the Sharpe ratio, the higher the level of alpha relative to unsystematic risk. As such, the highest weighting should go to Minster Mask and Costume, the second-highest to Kustom Auto, the third-highest to Imperial Shipyards, and the fourth-highest to Hearthstone. (Study Session 18, LOS 63.b, c)
Which of Zeller’s actions is least compatible with the use of the Treynor-Black model? His: A)
| support of the efficient market hypothesis. |
| | C)
| purchase of put options. |
|
Index funds appeal to efficient market theorists in part because they offer a low-cost way of investing in the market without trying to exploit infrequent mispricing. While active management of any sort may seem incongruous against the efficient market backdrop, it is active management, or the search for alpha, that clears up mispricings and theoretically leads to market equilibrium. The Treynor-Black model is an optimization framework that assumes markets are nearly efficient but does allow for some active management. The Treynor-Black model assumes a portfolio consisting of index funds, stocks, and the risk-free return. Put options have no place in that model. (Study Session 18, LOS 63.b)
Which of Zeller’s points is his weakest defense of the Treynor-Black model? A)
| In your portfolio, I overweight the stocks with the highest potential return to boost performance. |
| B)
| All of the stocks in your portfolio have betas below 1. |
| C)
| The strategy is designed to beat the market, but not necessarily to generate gains when the market is down. |
|
Strategies based on a mix of index funds and individual investments are not likely to generate gains during periods when the index falls, but they are still able to beat the market if the individual stocks are selected wisely. Zeller’s comment about diversification is true, and at the heart of the argument in favor of the Treynor-Black model. The statement about overweighting high-return stocks is not a particularly good argument, because the model also calls for underweighting stocks with high unsystematic risk. But the worst argument involves beta, because the Treynor-Black model doesn’t take beta into account directly. (Study Session 18, LOS 63.b)
In light of his observations about market movements, Zeller should: A)
| increase his cash allocation. |
| B)
| increase his index-fund allocation. |
| C)
| increase his allocation of actively managed stocks. |
|
As markets become more efficient, alphas shrink, and portfolio managers using the Treynor-Black model will reduce their allocation of actively managed stocks. However, Zeller expects mispricings to increase in the coming months, so he should step up the active management of his portfolios to take advantage of the higher alphas. (Study Session 18, LOS 63.c)
If Zeller stops assuming forecasts are accurate, he will most likely: A)
| increase the number of stocks in the portfolio. |
| B)
| reduce both risk and potential return of the portfolio. |
| C)
| shift subtly toward CAPM. |
|
The Treynor-Black model assumes forecasts are accurate. Relaxing that assumption requires analysts to place less weight on forecasts. If we discount the value of forecasted alpha, the weighting of the actively managed portion of the portfolio will decrease relative to the index. A higher index weighting is likely to reduce both risk and potential return. The less trust we have in forecasts, the more forecasted alpha is required to justify making a bet on an individual stock. Stocks with marginal alpha will become less appealing, so the number of stocks suitable for investment will decline. The number of stocks in the portfolio is more likely to decline than to increase. CAPM is very different from the Treynor-Black model, and accounting for inaccurate forecasts does not change that. Portfolio rebalancing is not relevant here. (Study Session 18, LOS 63.c)
Assuming Zeller intends to take positions in all four of the stocks discussed above, how many should he sell short?
While one of the stocks is expected to underperform, and two of the stocks have lower Sharpe ratios than the index, all have a positive expected alpha. As such, none should be shorted. (Study Session 18, LOS 63.b) |
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