This week’s lesson gives you a bit more time to
study the “Greeks” and how they are used. The lesson continues
to detail the material from last week’s lesson in terms of the
various pricing models and elements thereof.
Before moving any further into the material, please
spend plenty of time on “The Greeks” (aka option
sensitivities). Here are my lecture notes on this important
topic, along with some info on hedging:
Beta: a measure of how closely the movement of an individual stock tracks the movement of the entire stock market.
Gamma: Sensitivity
of Delta to unit change in the underlying. Gamma indicates an
absolute change in delta. For example, a Gamma change of 0.150
indicates the delta will increase by
0.150 if the underlying price increases or decreases by 1.0. Results may not be exact due to rounding.
Lambda: A measure of leverage.
The expected percent change in the value of an option for a 1
percent change in the value of the underlying product. Lambda/Leverage.
Rho: Sensitivity of option value
to change in interest rate. Rho indicates the absolute change in
option value for a one percent change in the interest rate. For
example, a Rho of .060 indicates the option's theoretical value will
increase by .060 if the interest rate is decreased by 1.0. Results
may not be exact due to rounding. Rho/Rate.
Theta: Sensitivity of option value
to change in time. Theta indicates an absolute change in the option
value for a 'one unit' reduction in time to expiration. The Option
Calculator assumes 'one
unit' of time is 7 days. For example, a theta of
-250 indicates the option's theoretical value will change by -.250
if the days to expiration is reduced by 7. Results may not be exact
due to rounding. NOTE: 7-day Theta changes to 1 day Theta if days to
expiration is 7 or less (see time decay). Theta/Time .
Vega (kappa, omega, tau): Sensitivity
of option value to change in volatility. Vega indicates an absolute
change in option value for a one percent change in volatility. For
example, a Vega of
.090 indicates an absolute change in the option's
theoretical value will increase by .090 if the volatility percentage
is increased by 1.0 or decreased by .090 if the volatility percentage
is decreased by 1.0. Results may not be exact due to rounding. Vega/Volatility.
Because BS OPM isolates the effects of each
variable’s effect on pricing, it is said that these isolated,
independent effects measure the sensitivity of the options value to
changes in the underlying variables.
Volatility
· Important factor in deciding what type of options to buy or sell.
· Shows the range
that a stock’s price has fluctuated in a certain period.
· Volatility is
denoted as the annualized standard deviation of a stock’s daily price
change.
Volatility Measures
· Statistical
Volatility - a measure of actual asset price changes over a specific
period of time ( a look - back)
· Implied
Volatility - a measure of how much the "market place" expects asset
price to move, for an option price. That is, the volatility that the
market itself is implying ( a look- ahead).
Implied Volatilities
· The implied
volatility calculated from a call option should be the same as that
calculated from a put option when both have the same strike price and
maturity.
More on Delta
· Delta (D)
describes how sensitive the option value is to changes in the
underlying stock price.
Change in option price = Delta
Change in stock price
More on Gamma
· Gamma (G) is the
rate of change of delta (D) with respect to the price of the
underlying asset.
· For example, a
Gamma change of 0.150 indicates the delta will increase by 0.150 if
the underlying price increases or decreases by 1.0.
Change in Delta = Gamma
Change in stock price
· Gamma can be either positive or negative
· Gamma is the
only Greek that does not measure the sensitivity of an option to one
of the underlying assets. – it measures changes to its Greek brother –
Delta, as a result of changes to the stock price.
More on Theta
· Theta (Q) of a
derivative is the rate of change of the value with respect to
the passage of time.
· Or sensitivity of option value to change in time
Change in Option Price = THETA Change in time to Expiration
· If time is measured in years and value in dollars, then a theta value of –10 means that as time to option expiration declines by .1 years, option value falls by $1.
· AKA Time decay:
o A term used to describe how the
theoretical value of an option "erodes" or reduces with the passage of
time.
More on Vega
· Vega (n) is the
rate of change of the value of a derivatives portfolio with respect to
volatility
· For example:
o a Vega of .090 indicates an absolute
change in the option's theoretical value will increase by .090 if
the volatility percentage is increased by 1.0 or decreased by
.090 if the volatility percentage is decreased by 1.0.
Change in Option Price = Vega
Change in volatility
· Vega proves to us
that the more volatile the underlying stock, the more volatile
the option price.
· Vega is always a positive number.
More on Rho:
· Rho is the rate of change of the value of a derivative with respect to the interest rate
· For example:
a Rho of .060 indicates the option's theoretical value will increase by .060 if the interest rate is decreased by 1.0.
Change in option price = RHO Change in interest rate
· Rho for calls is always positive
· Rho for puts is always negative
· A Rho of 25 means that a 1% increase in the interest rate would:
o Increase the value of a call by $.25
o Decrease the value of a put by $.25
business results.
Let's consider an example of foreign-currency
risk with ACME Corporation, a hypothetical U.S.- based company that
sells widgets in Germany. During the year, ACME Corp sells 100
widgets, each priced at 10 euros. Therefore, our constant assumption
is that ACME sells 1,000 euros worth of widgets:
When the dollar-per-euro exchange rate increases
from $1.33 to $1.50 to $1.75, it takes more dollars to buy one euro, or
one euro translates into more dollars, meaning the dollar is
depreciating or weakening. As the dollar depreciates, the same number
of widgets sold translates into greater sales in dollar terms. This
demonstrates how a weakening dollar is not all bad: it can boost
export sales of U.S. companies. (Alternatively, ACME could reduce its
prices abroad, which, because of the depreciating dollar, would not
hurt dollar sales; this is another approach available to a U.S.
exporter when the dollar is depreciating.)
The above example illustrates the "good news"
event that can occur when the dollar depreciates, but a "bad news"
event happens if the dollar appreciates and export sales end up being
less. In the above example, we made a couple of very important
simplifying assumptions that affect whether the dollar depreciation is
a good or bad event:
(1) We assumed that ACME Corp manufactures its
product in the U.S. and therefore incurs its inventory or production
costs in dollars. If instead ACME manufactured its German widgets in
Germany, production costs would be incurred in euros. So even if dollar
sales increase due to depreciation in the dollar, production costs
would go up too! This effect on both sales and costs is called a
natural hedge: the economics of the business provide their own hedge
mechanism. In such a case, the higher export sales (resulting when
the euro is translated into dollars) are likely to be mitigated by
higher production costs.
(2) We also assumed that all other things are equal, and often they are not. For example, we ignored
any secondary effects of inflation and whether ACME can adjust its prices.
Even after natural hedges and secondary effects,
most multinational corporations are exposed to some form of
foreign-currency risk.
In this example, the futures contract is a
separate transaction; but it is designed to have an inverse
relationship with the currency exchange impact, so it is a decent
hedge. Of course, it's not a free lunch: if the dollar were to weaken
instead, then the increased export sales are mitigated (partially
offset) by losses on the futures contracts.
Now let's look at the impact of the swap,
illustrated below. The swap requires JCI to pay a fixed rate of
interest while receiving floating-rate payments. The received
floating-rate payments (shown in the upper half of the chart below) are
used to pay the pre-existing floating-rate debt.
JCI is then left only with the floating-rate
debt, and has therefore managed to convert a variable-rate obligation
into a fixed-rate obligation with the addition of a derivative. And
again, note the annual report implies JCI has a "perfect hedge": The
variable-rate coupons that JCI received exactly compensates for the
company's variable-rate obligations.
Commodity or Product Input Hedge
Companies that depend heavily on raw-material inputs or commodities are sensitive, sometimes
significantly, to the price change of the inputs.
Airlines, for example, consume lots of jet fuel. Historically, most
airlines have given a great deal of consideration to hedging against
crude-oil price increases - although at the start of 2004 one major
airline mistakenly settled (eliminating) all of its crude-oil hedges: a
costly decision ahead of the surge in oil prices.
Monsanto (ticker: MON) produces agricultural
products, herbicides and biotech-related products. It uses futures
contracts to hedge against the price increase of soybean and corn
inventory: