Reading 1.8 Flashcards
Rebalancing portfolio
Buying & selling its assets to maintain its original asset allocation
Formula for The Time-t value, Vt, of a two asset portfolio
Vt = Ns * St + Mt * Bt
Formula for The Portfolio weights of equity and treasuries (2 assets)
Wt = (Nt * St) / Vt - first asset
1-Wt = (Mt * Bt) / Vt - second asset’s weight
Time t value before rebalancing
Vt-1 = Nt-1 * St + Mt-1 * Bt
Self Financing rebalancing Strategy definition and formula
1) Increased investment into one asset class is achieved by reducing investment into another asset class
2) (Nt -Nt-1) * St + (Mt - Mt-1) * Bt = 0.
Why are portfolios rebalanced?
Portfolio managers are driven to rebalance their portfolios based on their investment returns and their mandates
Buy and hold strategy rebalancing strategy
Portfolio manager does nothing, just establishes the initial asset allocation and hold it
Initial value of portfolio formula and future T value of portfolio formula
1) Vo = N0 * So + Mo * Bo
2) Vt = No * St + Mo * Bt
Constant mix strategy definition and what type of strategy is it and why?
The weight of each asset should stay the same
Contrarian because you sell the ones that have grown the most and buy those who grew the least
Constant mix strategy has a _____ payoff curve, why?
1) concave
2) Because of constant selling and buying
Which strategy, BH or CM outperforms in a volatile and non trending market?
CM - constant mix
For whom is the CM strategy best?
For constant risk averse investors
CPPI definition and type of strategy
1) Constant proportion portfolio insurance strategy is a rebalancing strategy that takes more risk (at least initially) than the BH strategy (and thus generates a reasonable long-term return) and ensures that the portfolio value generally does not fall below a pre-set floor.
2) it is a momentum strategy (opposite of contrarian): it increases the equity position after an increase in equity value, and reduces the position after a decline in equity value.
CPPI formula
St = mCt =m (Vt - Ft) and
Bt = Vt -St
What do the m and Ct stand for in the CPPI formula
1) m = multiplier
2) Cushion - different between floor Ft and portfolio value Vt at time t.
Ct = Vt - Ft
CPPI underperforms which rebalancing strategy in volatile and non trending market?
BH - buy and hold
CPPI outperforms which strategies in what markets?
Trending markets
CPPI is an optimal strategy for which type of investor?
Who’s risk tolerance increases as value of portfolio grows and decreases as portfolio shrinks
Which type is more classical CPPI, behaves like BH, behaves like CM
1) m>1 and F>0
2) m=1 and F>0
3) m<1 and F=0
1) classical CPPI
2) BH
3) CM
2 unique risks of CPPI compared to BH and CM
1) GAP RISK
• This is the risk that the CPPI’s floor is violated when equity value declines by more than 1/m. Gap risk is higher when markets are volatile and when the multiplier is large.
• For instance, a CPPI portfolio with a multiplier of 20 will violate its floor if its risky asset declines by more than 5% (= 1/20) between rebalancing periods.
2) Absorption risk
This risk occurs when the CPPI portfolio value reaches its floor and the portfolio liquidates its equity position. Since the portfolio does not participate in any subsequent recovery in equity values, it does not benefit when equity markets rebound.
3 Variations of the classical CPPI
1) Change the multiplier
2) Reset the floor
3) Stop Loss strategy
How does Change the multiplier variation of the CPPI strategy work? What is the result?
1) M may be expressed as a decreasing function (i.e. when volatility increases you decrease m) of the realized volatility using:
- the past n trading days
- value at risk
- expected shortfall
2) This reduces gap and absorption risk
How does the 2 Reset the Floor variation of the CPPI strategy work? Whats the second one called? Optimal equity position Formula?
1) Set the floor equal to X of the current portfolio value.
FORMULA: St = m* Vt * (1-x)
2) Set the floor equal to X of portfolio’s previous high water mark. TIPP - time invariant portfolio protection
FORMULA: St = m (Vt - xHt)
How does Stop-Loss variation of the CPPI strategy work? Advantage? Other variations?
Formula for equity position?
extreme case of CPPI: the portfolio invests entirely in the risky asset and, if the portfolio value hits the floor, the entire portfolio invests in the riskless asset.
Requires no rebalancing, suitable for when the cost of transactions are high or risky asset is not liquid
Some versions of stop loss allocate again to the risky asset if equity value exceeds Ft by a pre set amount
St =m * Vt { m=1 if Vt > Ft
m=0 if Vt <= Ft