碳費徵收政策宣告對國防產業股價之影響

The Impact of Carbon Fee Policy Announcements on Defense Industry Stock Prices

本研究旨在探討台灣環境部宣告「碳費三子法」期間，資本市場對國防產業類股之價格反應。選取40家上市櫃國防相關企業為樣本，運用事件研究法（Event Study）進行實證分析。實證結果顯示，儘管碳費政策意味著營運成本上升，但國防產業於政策宣告期間並未出現預期的負向異常報酬，反而在事件日呈現顯著之正向市場反應。本研究發現，此一抗跌韌性主要源於同期行政院通過創新高之國防預算案，形成了「政策抵銷效應（Policy Offsetting Effect）」。市場將國防自主政策下的剛性需求視為強大之基本面支撐，其正向評價足以稀釋環境監管帶來之成本衝擊。研究結果支持半強式效率市場假說與不確定資訊假說，顯示在綠色通膨與地緣政治雙重變局下，具備國家戰略支持之國防產業，已確立其作為資金避風港之防禦性資產特質。

This study investigates the capital market reaction to defense industry stocks following the announcement of the ''Three Carbon Fee Regulations'' by Taiwan's Ministry of Environment. Using a sample of 40 defense-related companies listed on the TWSE and TPEx, this study employs the event study methodology for empirical analysis. Empirical results indicate that, despite the implication of rising operating costs associated with carbon fee policies, the defense industry did not exhibit the expected negative abnormal returns during the announcement period. Instead, a significant positive market reaction was observed on the event day. This study attributes this resilience to a ''Policy Offsetting Effect'' driven by the Executive Yuan's concurrent approval of a record-high defense budget. The market views the inelastic demand arising from the policy of national defense autonomy as strong fundamental support, the positive valuation of which effectively dilutes the impact of environmental regulatory costs. These findings support both the Semi-strong Form Efficient Market Hypothesis and the Uncertain Information Hypothesis, demonstrating that amidst the dual challenges of greenflation and geopolitical instability, the defense industry—backed by national strategy—has established itself as a defensive asset and a capital safe haven.