this is for holding javascript data
Investment Math edited untitled.md
almost 8 years ago
Commit id: c46bf9ca0d1d6b2d697a1e67e370d48e422a3fdc
deletions | additions
diff --git a/untitled.md b/untitled.md
index a00c772..fa53e5d 100644
--- a/untitled.md
+++ b/untitled.md
...
Consider a portfolio which trades so as to keep the proportion of the risky asset at \(0 \lt \pi \lt 1\). A cppi overlay consists in protecting a certain level \(\underline{p}\) with I choose to set at \(1/2\) for illustration. I'll assume that the exposure to the risky asset is decreased linearly from \(\pi\) at \(p=1\) to zero at \(p=1/2\). This gives the following exposure to the portfolio:
\[\pi(p)=\pi-2(1-p),\, p \lt 1,\]
\[\pi(p)=\pi,\, p \geq 1.\]
The value function is easily obtained by solving:
\[\frac{dV}{V}=\pi(p)\frac{dp}{p}.\]
This leads to:
\[V(p)=p^{-\pi}\exp(2\pi(p-1)),\, p < 1,\]
\[V(p)=p^{\pi},\, p \geq 1.\]
The trading function is obtained by differentiation as usual:
\[n(p)=\pi(-1+2p)p^{-\pi-1}\exp(2\pi(p-1)),\, p < 1,\]
\[n(p)=\pi p^{\pi-1},\, p \geq 1.\]