本研究探討造市商的Gamma避險行為對股價波動性的影響。我利用台灣期貨交易所在2009年推出的股票選擇權造市商激勵計畫作為外生衝擊，並對2005至2011年間所有台灣期交所上市的股票選擇權進行斷點迴歸設計（Regression Discontinuity Design）模型。研究發現，造市商的負Gamma曝險每增加1單位，股價波動性將上升0.47個百分點，尤其是在中午交易時段。此外，我發現造市商對賣權及價外選擇權的避險需求對股價波動性的影響更為顯著。這些結果表明，該政策改變了造市商的報價行為，進而影響了整體股市的穩定性。

This study examines the impact of market makers' gamma hedging behavior on stock price volatility. I exploit the introduction of the stock options incentive program for market makers by the Taiwan Futures Exchange (TAIFEX) in 2009 as an exogenous shock, using Regression Discontinuity Design (RDD) model on all stock options listed on TAIFEX from 2005 to 2011. I find that a one-unit increase in market makers’ negative gamma exposure increases stock volatility by 0.47 percentage points, particularly during the noon trading interval. Additionally, I find that market makers’ hedging demand for put options and out-of-the-money options contributes more significantly to the increase in stock volatility. These findings suggest that the policy disrupted market makers’ quoting behavior, thereby affecting overall stock market stability.