6
$\begingroup$

Let $X_t$ be an american style financial derivative with random exercise time $T$ where $t$ and $T$ belongs to some finite set $A$.
Buying this derivative requires the buyer to pay $p_t$ up to time $T$.
Let $\Omega$ be the sample space of $X_t$, $p=(p_t)_{t \in A}$ the price process and $B={\left(C^A \right)}^\Omega$ the value space of $p$ for some set $C \subset \mathbb{R}$.
Assume expectation are taken under the risk-neutral measure with $R_t$ as the risk-free discounting factor from times $0$ to time $t$.
Is the no-arbitrage pricing process of the derivative given by $$ \arg_{p \in B} \left( \sup_{T \in A} E(X_T R_T - \int_0^T p_t R_tdt)=0 \right) \text{ (1)} $$

when $B$ requires that $p_t(\omega) \ne 0, t>0$ for some $\omega \in \Omega$?

My knowledge of finance tells me the no-arbitrage price would be $$ \sup_{T \in A} E(X_T R_T) \text{ (2)} $$ when B is degenerated to $p_0=k$ for some $k \in \mathbb{R}$ and $p_t=0,t \ne 0$.
Intuitively, I would expect (1) to be the natural extension to (2).
But is it theoretically true?
I searched, but I couldn't find any source confirming my hypothesis.

Thanks for any help.

Note: I asked this question on mathoverflow and I was guided here.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy