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Optimal exercise of russian options in the binomial model. Robert Chen Burton Rosenberg University of Miami. A Russian Option. Pays max price looking back. “Interest” penalty. Previous Work. Introduced by Shepp Shiryaev, Ann. Applied Prob., 1993.
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Optimal exercise of russian options in the binomial model Robert Chen Burton Rosenberg University of Miami
A Russian Option • Pays max price looking back. • “Interest” penalty Computational Finance 2006 Chen and Rosenberg
Previous Work • Introduced by Shepp Shiryaev, Ann. Applied Prob., 1993. • Analyzed in the binomial model by Kramokov and Shiryaev, Theory Prob. Appl. 1994. Computational Finance 2006 Chen and Rosenberg
Binomial Model Computational Finance 2006 Chen and Rosenberg
Arbitrage Pricing • Case of new maximum price: Computational Finance 2006 Chen and Rosenberg
The hedge • Receive 2su/(u+1) cash • Buy u/(u+1) shares stock at s • If up: • Sell stock for su2/(u+1) • Plus su/(u+1) cash gives su • If down: • Sell stock for s/(u+1) • Plus su/(u+1) cash gives s Computational Finance 2006 Chen and Rosenberg
Worked example • Stock prices and option values Computational Finance 2006 Chen and Rosenberg
Worked example … • Backward induction (apply formula) Computational Finance 2006 Chen and Rosenberg
Worked example … • Continue backwards: adapt pricing argument or use martingale measure Computational Finance 2006 Chen and Rosenberg
The full model • Time value r • Martingale measure and expectation Computational Finance 2006 Chen and Rosenberg
Option pricing formula • Liability at N: • Backward recurrence (=1/(1+r)): Computational Finance 2006 Chen and Rosenberg
Dynamic ProgramingSolution • Liability value at N, all j,k (actually k-j) • Work backwards N-1, N-2, etc. Computational Finance 2006 Chen and Rosenberg
Induction Theorems • First Induction Theorem • Second Induction Theorem • Monotonicity properties: expectation increasing in j and k. Computational Finance 2006 Chen and Rosenberg
Exercise boundary • Exercise decision depends only on delta between maximum and current prices • If k’-j’k-j then E(n,j,k)=nuk implies E(n,j’,k’)=nuk’ Computational Finance 2006 Chen and Rosenberg
Exercise boundary … • Least integer hnsuch that E(n,k-hn,k) obtains liability value. • If hn exists then hn’ exists for n≤n’≤N, and hn is decreasing in n. • In fact, 0≤hn-hn+1≤1. Computational Finance 2006 Chen and Rosenberg
Algorithm • Value of option depends essentially on delta between maximum and current prices • O(n2) for all values, O(n) to trace exercise boundary only Computational Finance 2006 Chen and Rosenberg
Algorithm … Computational Finance 2006 Chen and Rosenberg
The end • Thank you for your attention. • Questions? Comments? Computational Finance 2006 Chen and Rosenberg