backtests, and the first date (randomly selected) of
each bootstrapped period. This capital can be used to
purchase stocks or put options.
In the portfolios where no option positions are
taken, the portfolio will be fully invested in equities.
To find the weights in GMV case, the parameters,
namely the covariance matrix, are estimated using the
underlyings’ prior 12-month returns. Also, we set the
constraint of maximum weight to an individual name
to 20% and, for all stocks whose weight in the
optimization is lower than 0.2%, we set their weights
to be zero and redistribute them proportionally across
the remaining components in the portfolio. The
weights are re-calculated on every rebalancing date
(i.e. every 6 months, for both the backtests and the
bootstrap periods).
For the strategies that are long put options (with
the exception of the “SMI” strategy, that is long puts
on the SMI index and thus acting as a portfolio
“macro hedge”, explained in more detail below), a
target budget of 2.5% of portfolio value to be spent
on option premia on every rebalancing is set.
However, for the “absolute value signals” (i.e. not
relative ranking), such as trend, it is desirable to allow
a varying budget that is a function of the number of
underlyings with a signal, while keeping a limit.
Therefore, the methodology applied is as follows: at
t=0 and at each rebalancing date, a global budget is
set equal to 10% of the portfolio value (e.g., CHF 10
mio. at t=0). Then, this global budget is divided
equally among all the underlyings available (even
those with no weight in the GMV portfolio), which
represents the individual budget that will be spent to
purchase put options of that underlying if it shows a
negative signal. Note that, for relative (ranked)
signals, in which a 25% of underlyings show a signal
at each rebalancing date, a fixed 2.5% of portfolio
value is spent on each rebalancing (in reality, this
value ranges between 2.07% and 3.37%, due to
rounding the 25% to the closest number of
underlyings available, yet in most cases is between
2.3% and 2.8%). For “absolute signals”, the range is
between 0% if no underlying shows a signal and 10%
if all underlyings show a signal. On the historical
backtests, on average is spent 2.44% of portfolio
value at each rebalancing period for the trend signal,
2.10% for the IVOL-TS signal and 2.90% for the
SKEW-TS signal, close to the 2.50% target.
The strike is set at 90% of the spot price (OTM)
and maturity is always 6 months, coinciding with the
rebalancing period. The individual budget divided by
each estimated option premium sets the number of put
options that are purchased at each rebalancing date.
Note that, by using this method, the combination of
equities and put positions can be partially protective,
fully protective or even speculative (negative delta),
as the number of puts depends on the budget and the
premium, and not on the number of stocks in the
portfolio from each underlying.
The remaining capital available (portfolio value
minus the amount spent in option premia) is used to
purchase stocks.
The following trading strategies are simulated and
compared:
BASE: Base portfolio. It is an equity-only
portfolio, with no options. It serves as the benchmark.
OPT: At t=0 and each rebalancing date, it buys
put options on individual names that show a negative
signal.
LEV: It is constructed as the OPT strategy but
with 20% leverage. Thus, the initial invested capital
is CHF 120 million. It assumes a leverage cost of
SARON + 40 bps, paid at each rebalancing period.
The idea is that the risk reduction obtained from the
options’ protection can be used to leverage the equity
portfolio and its long-term return.
TR1: It is built as the OPT strategy. Yet, during
the investment period (i.e., between one rebalancing
date and the next one), an additional trading rule is
added (TR1): If an option’s delta reaches a pre-
defined trigger (-0.9 or less), the put that was initially
bought is sold to close the position at a profit. The aim
of this rule is that, in the case of a short-term upside
reversal, the profit that is made in the options’
positions is not lost with the reversal.
TR2: It is a variation of TR1: once an option’s
delta reaches the predefined trigger, if the negative
signal is still present in the underlying, it won’t close
the positions. If the signal is positive or neutral, it will
close the positions as in TR1. This trading rule is
implemented in the backtests only.
TR3: It is built as the OPT strategy, in which put
options are bought on stocks that show a negative
signal, but with an additional rule: if the implied
volatility of any option is below 10% (i.e., low
implied volatility), it will purchase the put options,
regardless of whether the underlying shows negative
signal or not. Likewise, if the implied volatility is
above 30% (i.e., high implied volatility), it won’t
purchase the put options even if they show a negative
signal. This additional rule buys options when they
are cheap and avoids them when they are expensive,
regardless of the signal.
WEI.: This strategy does not take option
positions. Instead, it sets the weights of the
underlyings with a negative signal at zero and
redistributes these weights proportionally across the
remaining components in the portfolio.