Market-Bench: Benchmarking Large Language Models on Economic and Trade Competition

The ability of large language models (LLMs) to manage and acquire economic resources remains unclear. In this paper, we introduce $\mathbf{\text{Market-Bench}}$, a comprehensive benchmark that evaluates the capabilities of LLMs in economically-relevant tasks through economic and trade competition. Specifically, we construct a configurable multi-agent supply chain economic model where LLMs act as retailer agents responsible for procuring and retailing merchandise. In the $\mathbf{\text{procurement}}$ stage, LLMs bid for limited inventory in budget-constrained auctions. In the $\mathbf{\text{retail}}$ stage, LLMs set retail prices, generate marketing slogans, and provide them to buyers through a role-based attention mechanism for purchase. Market-Bench logs complete trajectories of bids, prices, slogans, sales, and balance-sheet states, enabling automatic evaluation with economic, operational, and semantic metrics. Benchmarking on 20 open- and closed-source LLM agents reveals significant performance disparities and winner-take-most phenomenon, $\mathit{\text{i.e.}}$, only a small subset of LLM retailers can consistently achieve capital appreciation, while many hover around the break-even point despite similar semantic matching scores. Market-Bench provides a reproducible testbed for studying how LLMs interact in competitive markets.