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Rho
is one of the
Greek factor sensitivities used by traders to
measure market risk exposures in derivatives
portfolios. It measures a portfolio's linear exposure to changes
in the risk-free interest rate.
Let
and
be current
values for the portfolio and underlier (here superscripts 0 indicate the
current time t = 0. See the
notation conventions documentation). Formally, rho is the partial derivative of the portfolio's
value with respect to the risk-free rate:
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[1] |
This technical definition
leads to an approximation for the behavior of a portfolio.
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[2] |
where
is a small
change in the risk-free rate, and
is the corresponding change in the portfolio's value.
Suppose a portfolio has a rho of
USD –2.3MM. If
the risk free rate rises 5 basis points (
= .0005), the portfolio should lose about
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2.3MM (.0005) = USD 1150 |
[3] |
For most portfolios, sensitivity to the risk-free rate is minor
compared to possible sensitivities to underliers or
implied volatilities.
For this reason, rho is a less significant Greek.
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