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Pricing Swing Options. Alex, Devin, Erik, & Laura. Intro: Swing Options. Holder has right to exercise N times during period [T 0 , T] When N = 1 , identical to American Option Separated by minimum refraction time τ R Prevents multiple exercising at one time instant
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Pricing Swing Options Alex, Devin, Erik, & Laura
Intro: Swing Options • Holder has right to exercise N times during period [T0, T] • When N = 1, identical to American Option • Separated by minimum refraction time τR • Prevents multiple exercising at one time instant • If expected payoff is not optimal, one should not exercise • However, waiting too long prevents use of all exercise rights • At a given node, one may: • a) Exercise, collect payoff with (N – 1) times left to exercise after τR • b) Not exercise, collect no payoff but maintain ability to exercise at any moment • Bounds • Lower: Series of European Options • Upper: Series of American Options
Intro: Energy Applications • Also referred to as “Take-or-Pay”, “Variable Volume”, or “Variable Take” Options • Usually a Dual Option • Complex patterns of consumption and limited storability of commodities create need to hedge for pricing and demand spikes • Allow holder to repeatedly choose to receive or deliver a specified amount of commodity • A penalty function may be applied if the exchanged amount is outside the set boundary • When the penalty function is non-zero, the Swing Option can no longer be approximated or bounded by American or European Options • A seasonality factor may be applied to create a mean-reverting process
Intro: Finance Applications • Relatively new to Stock Market • Similar to Flexi-Options which hedge against interest rate spikes • Similar to Multi-Callable Options • In contrast to Energy Market, “Bang-Bang” Control • When the market suggests that it is best to exercise, you will exercise as much as possible • Not limited by season, weather, storage capacity, etc.
Intro: Pricing Methods in Literature • Dynamic Programming • Binomial Forest/Multi-Layered Tree • Our method • Jaillet, Ronn, & Tompaidis (2003) • Sequence of Multiple Optimal Stopping Problems • Solved by Hamilton-Jacobi-Bellman Variational Inequalities (HJBVI) • Dahlgren & Korn (2003) • Above method reduced to cascade of Stopping Time Problems • Finite Element Analysis • Wilhelm & Winter (2006)
Theory: Swing Call Options • Bounded above by strip of N American options • Bounded below by a strip of N European options • For a Swing Call with N exercise rights: • Same price as a strip of N European options with maturities Ti = T – (i – 1) τR, i = 1, ... , N, where τR is the recovery period
Theory: Swing Put Options • Let PN(St) = the price of a swing option with N rights where St = the price of the stock at time t • Let g(St) = (K – St)+ denote the payoff function of the swing put where K is the strike price • Let{ θi }, i = 1, ... , N, t ≤ θi ≤ T, θi+1+ τ ≤ θi be the set of allowable optimal exercise times • The price of a swing option is given by: (For proof of existence see M. Dahlgren and R. Korn, The Swing Option On The Stock Market, International Journal of Mathematical Finance Vol. 8. No.1 (2005) )
Theory: Swing Put/Call Options • Previous formula works for Call Options but the set of optimal exercise times will be θi = T-(N-i)τR, i = 1, ... , N • For a dual-style swing option g(St) = abs(St-K)
Algorithm: Naïve Pricing of American Call • F(0,0) is the option price • Can be implemented directly, no real thinking involved
Algorithm: Naïve Pricing of American Call • F(0,0) is the option price • Can be implemented directly, no real thinking involved • TOO SLOW
Algorithm: Naïve Pricing of American Call • We compute things more than once • Complexity is O(2^N)
Algorithm: Dynamic Programming • Identical subproblems should be solved only once • Work backwards, save intermediate results • This is just how one would price an option by hand • Complexity is O(N^2)
Algorithm: Overview of Implementation • Recursive computation converted to iterative computation • Results stored in a giant (n+1)x(n+1) array • Work backwards, from the (known) values to our desired price
Algorithm: Swing Option • Much messier! • Fundamental principles of pricing the American Call still apply • Naïve approach is NOT computationally feasible
Algorithm: Swing Option – The Good • We can directly translate this into an iterative problem, working backwards and saving intermediate results • Complexity is O(N^3 * C * D) • For the most part, this is good enough
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