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2. Performance Evaluation. We want to know whether a particular portfolio performance is abnormally highWhat is abnormal?Market adjusted, or market model adjustedReward to risk measures such as the Sharpe ratioComplicated issueMany kinds of different benchmarks and measuresDifferent measures may lead to different implications on performance evaluation.
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1. Chapter 20 Performance Evaluation and Active Portfolio Management
2. 2 Performance Evaluation We want to know whether a particular portfolio performance is abnormally high
What is abnormal?
Market adjusted, or market model adjusted
Reward to risk measures such as the Sharpe ratio
Complicated issue
Many kinds of different benchmarks and measures
Different measures may lead to different implications on performance evaluation
3. 3 Two ways of performance evaluation 1) Relative performance measures
Compare with other benchmark with similar risk characteristics
(Ex) high-yield bond portfolio
growth stock portfolio
2) Risk-adjustment based on MV or CAPM
Sharpe measure
Treynor measure
Jensen measure
4. 4 Sharpe Measure 1) Sharpe measure =
5. 5 Treynor Measure 2) Treynor Measure =
6. 6 Jensens Alpha
7. 7 M2 Measure Attempt to resolve the difficulty in the interpretation of the Sharpe measure by translating it into a percentage term
Developed by Modigliani and Modigliani (Modigliani-squared)
Equates the volatility of the managed portfolio with the market by creating a hypothetical complete portfolio, rp*, made up of T-bills and the managed portfolio:
M2 = rp* rm
where rp* is the return on the hypothetical portfolio
If the risk is lower than the market, leverage is used and the hypothetical portfolio is compared to the market
8. 8 M2 Measure: Example
9. 9 T2 Measure Similar to the M2 measure, it converts the Treynor measure into percentage return basis
Makes it easier to interpret and compare
Equates the beta of the managed portfolio with the markets beta of 1 by creating a hypothetical portfolio made up of T-bills and the managed portfolio
T2 = Rp* Rm
where Rp* is the excess return on the hypothetical portfolio
If the beta is lower than one, leverage is used and the hypothetical portfolio is compared to the market
10. 10 T2 Example
11. 11 Which Measure is Appropriate? It depends on investment assumptions
1) If the portfolio represents the entire investment of an individual, then total volatility matters
Thus, Sharpe measure is appropriate, which can be compared to that of the market
2) If a portfolio is just one of a whole portfolio, then systematic risk matters
Thus, use the Treynor or the Jensen a measure
12. 12 Limitations of the model-based performance measures Assumptions underlying measures limit their usefulness
Parameter stability
When the portfolio is being actively managed, this stability requirement is not met
Practitioners often use benchmark portfolio comparisons to measure performance
13. 13 Performance Attribution Decomposing overall performance into components that are related to specific elements of performance
Asset allocation decision
Market timing
Up and Down Markets
Security selection decision
Sectors or industries
Individual companies
14. 14 Decomposition of Performance Attribution Assume two broad asset markets, (1) stocks & (2) bonds.
Want to compare a managed portfolio return (rp) with a benchmark portfolio return (rm)
rp rm = (wp1rp1 + wp2rp2) (wm1rm1 + wm2rm2)
= (wp1 wm1)rm1 + (wp2 wm2)rm2 ? asset alloc.
+ wp1(rp1 rm1) + wp2 (rp2 rm2) ? sec. selec.
Difference in weights leads to asset allocation bets, and difference in returns within asset classes leads to security selection bets
15. 15 Asset allocation vs. Selection (1) (2) (3) (4) (5)=(3)×(4)
Portfolio Benchmark Excess Index contribution to
Market weight weight weight return performance
Stocks 0.7 0.6 0.1 5.81% 0.581%
Bonds 0.07 0.3 -0.23 1.45% -0.3335%
Cash 0.23 0.1 0.13 0.48% 0.0624%
Contribution of asset allocation 0.3099%
(1) (2) (3) (4) (5)=(3)×(4)
Portfolio Benchmark Excess Portfolio contribution to
Market return return return weight performance
Stocks 7.28 5.81 1.47 0.7 1.03%
Bonds 1.89 1.45 0.44 0.07 0.03%
Contribution of selection within markets 1.06%
16. 16 Lure of Active Management Are markets really efficient?
Some managers outperform the market for extended periods, and investors are willing to pay for expensive analysis
The abnormal performance may not be too large, but it is too large to be attributed solely to noise
Markets are nearly efficient
Evidence of anomalies exists
Turn of the year effect, small firm effect, momentum effect
? The evidence suggests that there is some role for active management
17. 17 Market Timing What is market timing?
Adjust the portfolio weights according to a forecast of the market movements for next period
(EX) Shift between stocks, bond, and money market instruments
Results: higher returns, lower risk (downside is eliminated)
With perfect ability to forecast, the portfolio return behaves like an option
The value of perfect market timing ability is equivalent to the value of a call option
18. 18 Rate of Return for a Perfect Market Timer
19. 19 How to judge timing ability? Need long horizon to judge the ability
Judge proportions of correct calls
Bull markets and bear market calls
See if managers adjust portfolios for up and down movements in the market
Low Market Return ? low ßeta
High Market Return ? high ßeta
20. 20 Example of Market Timing
21. 21 Style Analysis Introduced by Bill Sharpe
Explain percentage returns attributable to style investment
Size effect
Value vs. growth
Momentum
Style Analysis has become popular with the industry
22. 22 Morning Stars Risk Adjusted Rating Similar to mean Standard Deviation rankings
Companies are put into peer groups
Stars are assigned
1-lowest
5-highest
Highly correlated to Sharpe measures
23. 23 Active portfolio management Concentrate funds in undervalued stocks, sectors, or industries
Active selection procedure results in taking some unsystematic risk
Balanced funds in an active portfolio and in a passive portfolio
Some portion based on passive strategy, and the rest based on active strategy
(Ex) Treynor/Black model
24. 24 Treynor-Black Model Model used to combine actively managed stocks with a passively managed portfolio
Optimal combination of active and passive portfolios can be determined, based on a reward-to-risk measure that is similar to the the Sharpe Measure
Assumptions
Analysts have a limited ability to find a select number of undervalued securities
Portfolio managers can estimate the expected return and risk for the actively-managed portfolio as well as the broad market portfolio (passively managed)
25. 25 Reward-to-Variability Measure
26. 26 Appraisal Ratio
27. 27
28. 28 Summary: Treynor-Black Model Sharpe ratio can be increased by active management with added ability to pick stocks
Slope of new CAL > CML
(rp-rf)/sp > (rm-rf)/sp
P is the portfolio that combines the passively managed portfolio with the actively managed portfolio
The combined efficient frontier has a higher return for the same level of risk