Auditing Asset-Specific Preferences in Financial Large Language Models: Evidence from Bitcoin Representations and Portfolio Allocation
审计金融大语言模型中的资产特定偏好:来自比特币表征与投资组合配置的证据
Wenbin Wu
AI总结 本研究通过三级审计协议,发现大型语言模型对比特币存在框架依赖的偏好,并识别出模型内部一个可因果干预的比特币选择性特征,该特征能显著影响下游投资组合配置。
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大型语言模型现已驱动机器人顾问和交易代理,但它们是否对特定资产存在固有偏见尚未得到充分检验。我们提出三个问题:LLMs是否系统性地偏好某些金融工具;能否识别出对这些偏好具有因果杠杆作用的内部表征;以及该表征是否影响下游金融决策。我们开发了一个三级审计协议并将其应用于比特币。首先,对八个前沿LLMs的行为审计显示,比特币在货币类工具中的排名具有框架依赖性:模型将其置于“可靠货币”的第5位(共8位),但在危机和自主代理框架下接近榜首,且属性交换实验确认排名追踪功能属性而非名称。其次,我们打开模型内部:在Gemma 3中搜索数千个稀疏自编码器特征,识别出一个主导的比特币选择性特征。放大该特征会使模型偏向该资产,抑制则使其远离,即使提示中从未出现“比特币”。第三,我们测试金融后果:放大使比特币在投资组合中的份额提高5.2个百分点,而抑制降低4.6个百分点,放大在加密资产内重新分配,抑制则削减总加密敞口。我们将此描述为有界行为杠杆(杠杆指对输出的因果影响,而非金融杠杆):一个可识别的内部特征可被扰动以改变金融选择,但仅在可测量的限度内。该框架将内部表征与外部建议联系起来,并通过随机对照和机制边界进行验证。随着LLMs成为自主金融代理,这是迈向新兴“了解你的代理”(KYA)标准的行为层的第一步:了解代理偏好什么,以及该偏好可被移动多远。
Large language models now power robo-advisors and trading agents, yet whether they carry built-in biases toward specific assets is largely untested. We ask three questions: do LLMs systematically prefer certain financial instruments; can an internal representation with causal leverage over those preferences be identified; and does that representation affect downstream financial decisions? We develop a three-level audit protocol and apply it to Bitcoin. First, a behavioral audit of eight frontier LLMs shows that Bitcoin's ranking among money-like instruments is frame-dependent: models place it around rank 5 of 8 as "reliable money" but near the top under crisis and autonomous-agent frames, and an attribute-swap experiment confirms rankings track functional properties, not names. Second, we open a model's internals: a search across thousands of sparse-autoencoder features in Gemma 3 identifies a dominant Bitcoin-selective feature. Amplifying it shifts the model toward the asset and suppressing it shifts the model away, even when "Bitcoin" never appears in the prompt. Third, we test financial consequences: amplification raises Bitcoin's portfolio share by 5.2 percentage points while suppression lowers it by 4.6 pp, with amplification reallocating within crypto and suppression cutting total crypto exposure. We characterize this as bounded behavioral leverage (leverage meaning causal influence over outputs, not financial leverage): an identifiable internal feature can be perturbed to move financial choices, but only within measurable limits. The framework links internal representations to external recommendations, validated with random controls and mechanism boundaries. As LLMs become autonomous financial agents, this is a first step toward a behavioral layer for emerging know-your-agent (KYA) standards: knowing what an agent prefers, and how far that preference can be moved.