The QLBS Model Within the Presence of Feedback Loops Through the Impacts of a Large Trader


Özsoy A. U., UĞUR Ö.

Computational Economics, 2025 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Publication Date: 2025
  • Doi Number: 10.1007/s10614-025-10936-x
  • Journal Name: Computational Economics
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Social Sciences Citation Index (SSCI), Scopus, IBZ Online, International Bibliography of Social Sciences, ABI/INFORM, EconLit, INSPEC, zbMATH
  • Keywords: Agent-based modeling, Batch-mode reinforcement learning, Fitted Q-iteration, FX option pricing, Large trader, Market impacts, QLBS
  • Middle East Technical University Affiliated: Yes

Abstract

We extend the QLBS model by considering a large trader whose transactions leave a permanent impact on the exchange rate process and therefore affect the price of contingent claims on such processes. Through a hypothetical limit order book we quantify the exchange rate altered by such transactions. We therefore define the quoted exchange rate process, for which we assume the existence of a postulated hedging strategy. Given the quoted exchange rate and postulated hedging strategy, we find an optimal hedging strategy through batch-mode reinforcement learning given the trader alters the course of the exchange rate process. We assume that the trader has its own concept of fair price and we define our problem as finding the hedging strategy with much lower transaction costs yet delivering a price that well converges to the fair price of the trader. We show our contribution results in an optimal hedging strategy with much lower transaction costs and convergence to the fair price is obtained assuming sensible parameters.