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1
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2
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- How to get inferior results:
- GICS as savings plans
- LTCM over-leverage
- Telecommunications mania
- Even good tools need guidance:
- Optimal Asset Allocation
- Risk budgets
- Value-at-Risk
- Risk fundamentals:
- Volatility drives down median results
- One succeeds by growing discretionary wealth, or the margin of safety
- How should these principles affect risk management?
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3
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- If you invest $1 in a leveraged hedge fund whose return each year is an
equal chance of:
- What return do you expect to get each year?
- What distribution of wealth will you actually achieve in 10 years?
- How could you improve the median result?
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4
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- Monte Carlo simulation of the impact of different leverages where:
- Log-normal returns
- Mean excess stock return: .06
- Return variance: .202
- Leverages = 0.75, 1.5, 3.0
- Rule of thumb: set your leverage ratio at excess return mean divided by
variance, here .06/.04 = 1.5.
- This leverage ratio should be applied only to your margin of safety or
discretionary wealth.
- Example: 40% discretionary
wealth here implies a 60% allocation to stocks.
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5
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- Should we always rank active managers based on information ratios?
- Manager A: alpha 6%, tracking error 8%, IR=0.75.
- Manager B: alpha 5%, tracking error 1%, IR=5.0
- Who would better manage your entire portfolio?
- Extending our prior example indicates A.
- Median return predicted from growth model: mean total return –
variance/2.
- IR didn’t take into account leverage inflexibility.
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6
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- Fraction in stocks = k*(wealth-floor)
- Typical:
- k=5
- floor=0.8*initial wealth
- Constraint against borrowing
- Why do a large number of users get stuck, in real terms, near the floor?
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7
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- Most of the investment literature focuses on the obvious problems
created by pricing jumps and illiquidity.
- But if one focuses on the expected growth rate of the safety margin …
- It is also clear that the amplification of the impact of price moves on
holdings (leverage) is often too high.
- Resulting in negative expected growth of the margin of safety.
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8
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- Rebalance:
- Among risky assets for efficient diversification
- Between cash and risky assets
- when excess return mean is less
than its variance
- when the impact on your margin of safety is compensated by changes in
expected returns.
- Follow stop-loss rules between risky assets and cash for losses and
raise risk allocation after gains when all these conditions prevail:
- Your gains and losses are not compensated by changes in expected return
- Excess return mean is greater than its variance.
- Position amplification relative to returns is not excessive relative to
optimal leverage.
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9
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- Total portfolio VaR shows substantial negative skew, as when writing
index calls, or very fat-tailed return distributions, as when hedging
using uncertain return correlations, or …
- Risky asset exposure relative to the margin of safety must be held at
far-above-normal leverage ratios, or …
- Considering costly portfolio insurance.
- For these cases, you need to quantify the impact of return skew and
kurtosis on median compound outcomes.
That is, more fully consider downside risk.
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10
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- Selecting the most appropriate risk tolerance in asset allocation
studies.
- Quantifying the long-term growth benefits of diversification.
- Assessing the contribution of active managers.
- Deciding when to re-balance risky assets.
- Reacting to major changes in margin of safety.
- Designing better downside protection.
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