Trading Prophets with Initial Capital

Fuente: arXiv
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Autori principali: Azar, Yossi, Buchbinder, Niv, Levin, Roie, Vardi, Or
Natura: Preprint
Pubblicazione: 2025
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author Azar, Yossi
Buchbinder, Niv
Levin, Roie
Vardi, Or
author_facet Azar, Yossi
Buchbinder, Niv
Levin, Roie
Vardi, Or
contents Correa et al. [EC' 2023] introduced the following trading prophets problem. A trader observes a sequence of stochastic prices for a stock, each drawn from a known distribution, and at each time must decide whether to buy or sell. Unfortunately, they observed that in this setting it is impossible to compete with a prophet who knows all future stock prices. In this paper, we explore the trading prophets problem when we are given initial capital with which to start trading. We show that initial capital is enough to bypass the impossibility result and obtain a competitive ratio of $3$ with respect to a prophet who knows all future prices (and who also starts with capital), and we show that this competitive ratio is best possible. We further study a more realistic model in which the trader must pay multiplicative and/or additive transaction costs for trading which model dynamics such as bid-ask spreads and broker fees.
format Preprint
id arxiv_https___arxiv_org_abs_2510_16516
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Trading Prophets with Initial Capital
Azar, Yossi
Buchbinder, Niv
Levin, Roie
Vardi, Or
Data Structures and Algorithms
Computer Science and Game Theory
Correa et al. [EC' 2023] introduced the following trading prophets problem. A trader observes a sequence of stochastic prices for a stock, each drawn from a known distribution, and at each time must decide whether to buy or sell. Unfortunately, they observed that in this setting it is impossible to compete with a prophet who knows all future stock prices. In this paper, we explore the trading prophets problem when we are given initial capital with which to start trading. We show that initial capital is enough to bypass the impossibility result and obtain a competitive ratio of $3$ with respect to a prophet who knows all future prices (and who also starts with capital), and we show that this competitive ratio is best possible. We further study a more realistic model in which the trader must pay multiplicative and/or additive transaction costs for trading which model dynamics such as bid-ask spreads and broker fees.
title Trading Prophets with Initial Capital
topic Data Structures and Algorithms
Computer Science and Game Theory
url https://arxiv.org/abs/2510.16516