Do Gasoline Mergers Affect Consumer Prices? The Marathon Ashland Petroleum and Ultramar Diamond Shamrock Transaction
研究了1999年马拉松阿什兰石油收购超星钻石三叶草在密歇根州的资产后，是否导致汽油零售价上涨，采用双重差分模型比较受影响与未受影响城市的价格变化，未发现涨价证据。
In 1999, Marathon Ashland Petroleum (MAP) acquired the Michigan assets of Ultramar Diamond Shamrock (UDS), which increased MAP's share of terminal storage in Michigan from about 16 percent to about 25 percent and increased the share of gasoline stations bearing a MAP brand from about 16 percent to about 24 percent. In this paper, we examine whether this acquisition affected the retail price of gasoline. We use a difference-in-differences model to compare price movements in six Michigan cities affected by the acquisition with price movements in two nearby cities unaffected by the acquisition. Using this model, we find no evidence that this acquisition led to higher prices for consumers. .