本文包含了两篇关于金融分析师和公司治理的实证研究。第一篇论文（题目为"分析师影响公司避稅吗？来自自然实验的证据"）研究金融分析师对企业避稅的影响。基本回归结果表明追踪公司的分析师越多，公司避稅越少。通过充分利用券商倒闭和券商兼并这两个对金融分析师数量造成的外生冲击，我们利用双重差分的分析方法发现，相比同类公司，经受分析师数量外生下降的公司将从事更多的避稅活动。因此，证据充分表明分析师的数量对企业避稅具有强烈的负面因果影响。我们进一步发现，这一负的因果影响主要集中在本来拥有较少分析师和融资受到约束的公司。此外，在财务信息不透明和企业管制较差的公司，效果也更为明显。综上，该论文提供了新的数据表明，财务信息透明度对于企业避稅具有重要作用。当遭遇外生的分析师下降从而引起信息透明度降低的情况下，公司会更为激进的避稅。 / 第二篇论文（题目为"金融分析师影响公司治理吗？来自自然实验的证据"）利用跟第一篇论文相同的两个自然实验（券商倒闭和券商兼并），进一步探讨了分析师对公司治理的作用。我们发现，当追踪一个公司的金融分析师数量受到这两个自然实验的影响而减少之后，该公司内部现金持有量给股东带来的边际价值减少，其CEO获得更高的超额报酬，其管理层更有可能做出破坏公司价值的收购决策，其管理层更有可能从事盈余管理活动。重要的是，我们发现这些影响主要集中在本来拥有较少分析师和较少市场竞争压力的公司。我们进一步发现，本来拥有较少分析师的这些公司在受到券商倒闭和券商兼并的冲击下，其CEO的报酬和超额报酬对公司业绩较原来更不敏感。这些发现与我们的分析师监督假说是一致的，即金融分析师发挥着审查管理者行为的重要公司治理作用。当公司损失分析师之后，市场在对公司股票定价时会考虑公司因此而产生的代理成本的增加。 / This thesis consists of two empirical studies on financial analysts and corporate governance. The first essay (titled "Does Analyst Coverage Affect Tax Avoidance? Evidence from Natural Experiments") investigates the effects of analyst coverage on corporate tax avoidance. The baseline results indicate that analyst coverage reduces tax avoidance. Using a Difference-in-Differences approach based on two sources of exogenous shocks to analyst coverage - broker closures and mergers, we find that firms engage in more tax avoidance activities after an exogenous drop in the number of analysts following the firm, compared to similar firms that do not experience an exogenous drop in analyst coverage. The evidence therefore suggests a strong negative causal effect of analyst coverage on tax avoidance. We further find that the effects are mainly driven by the firms with smaller initial analyst coverage and more financial constraints. Moreover, the effects are more pronounced in the subset of firms with more information opacity and poorer corporate governance. Overall, the findings suggest that analyst coverage materially and causally affects tax avoidance. Our paper offers novel evidence that information transparency plays an important role in corporate tax avoidance decisions, and with increased information opacity induced by exogenous drops in analyst coverage, firms are likely to avoid tax more aggressively. / The second essay (titled "Do Analysts Matter for Governance? Evidence from Natural Experiments") further explores the causal effects of analyst coverage on mitigating managerial expropriation of outside shareholders, building on the same two natural experiments - broker closures and mergers. We find that as a firm experiences an exogenous decrease in analyst coverage, shareholders value internal cash holdings less, its CEO receives higher excess compensation, its management is more likely to make value-destroying acquisitions, and its managers are more likely to engage in earnings management activities. Importantly, we find that most of these effects are mainly driven by the firms with smaller initial analyst coverage and less product market competition. We further find that after exogenous brokerage terminations, a CEO’s total and excess compensation become less sensitive to firm performance in firms with low initial analyst coverage. These findings are consistent with the monitoring hypothesis, specifically that financial analysts play an important governance role in scrutinizing management behavior, and the market is pricing an increase in expected agency problems after the loss in analyst coverage. / 1. Does analyst coverage affect tax avoidance? : evidence from natural experiments -- 2. Do analysts matter for governance? : evidence from natural experiments. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Chen, Tao. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references. / Abstracts also in Chinese.