股權質押作為一種融資方式，股東在面臨資金需求時，可以將自身的股票進行質押以獲取融資。同時由於股權質押並不影響股東在公司的所有權，因此對股東的控制權不會產生較大的影響。因而在股權質押被中國政府與市場認可後，有較多的股東進行股權質押以獲取融資。在2013年前，股東進行股權質押僅僅可以通過場外質押，即向銀行、信託等機構以股權作為質押物進行抵押貸款，但是由於銀行等機構以傳統非標準化信貸業務為主，以及其風險偏好等因素導致股權質押融資方式門檻較高，流程複雜，可操作性相對較低。自2013年開始，中國證監會開始允許場內質押業務，即允許上市公司股權向證券公司進行股票質押融資。由於監管的鼓勵，證券公司相較銀行等金融機構其本身風險偏好也更高，且券商對公司的股票處理等相對較為熟悉，因而中國的股權質押市場開始蓬勃發展。但在2014年末到2015年，中國股市經歷了牛市與熊市。在這段時期，由於股東可以通過股票質押施加杠杆來放大收益與損失，由此導致股市價格的快速波動與市場的風險集聚增大。而在這個過程中，由於股價的下跌，導致部分股東的質押股票資不抵債，股票被強制平倉，進一步加劇了股票市場的波動。此外，由於多數上市公司參與股權質押，在2017年甚至有部分公司出現了接近“全股質押”的現象，資本市場隨著上市公司股價的下行和質押比例的高位，風險“螺旋式”放大。為了緩解資本市場的風險與化解公司的財務困境，2018年底中國政府提出了一系列以緩解上市公司股權質押風險為核心的資金“紓困”計畫。

股權質押作為一種融資手段，能夠拓寬公司與個人的融資管道，但是同時也帶來了一系列其他的問題。因而，股權質押成為了學術界與業界關注的焦點。而公司的控股股東進行股權質押的動機是什麼樣的？股權質押直接對公司產生的績效影響如何？股權質押對股票的波動產生什麼樣的影響？後期中國政府提出的“紓困”計畫的影響如何？這些問題目前尚未有充足的研究進行揭示。為了彌補此方面的不足，本文聚焦於中國A股上市公司的股權質押，對這些問題展開了探究。

本文利用中國A股上市公司2003年到2018年的數據，首先探討了股權質押的重要動機之一，融資約束問題，即探究融資約束對公司大股東進行股權質押行為的影響；其次，本文探討了上市公司的大股東進行股權質押的影響，分別從公司的財務績效與市場績效展開研究；此外，本文進一步分析了大股東的股權質押行為對公司股票波動風險的影響，並進一步探討了在熊市過程中的影響；最後，本文分析了股票市場對公司接受政府“紓困”計畫的市場反應。

本文的研究結論主要如下：（1）本文研究表明融資約束越嚴重的公司中，大股東採取股權質押的融資行為的比例越高。通過與後文的分析，本文發現大股東進行股權質押的一個重要原因是融資管道受限，被迫採用股權質押融資方式。同時，其還可能存在為了自身的利益，而非解決公司的財務困境方面動機進行股權質押行為；（2）大股東質押股份比例越高的公司中，公司下一年的財務績效與市場績效越差。結果證明控股股東的股權質押對公司的財務與股價表現均產生了較差的影響。這個結果同時也進一步證明了控股股東的股權質押可能是大股東基於控制權私利對中小股東的剝削；（3）大股東質押比例高的公司面臨的股價波動性也更高，且在熊市中，這一關係會被進一步放大。這個結果表明，大股東的股權質押行為會加劇股票市場的風險，且在熊市的過程中，股權質押的負向影響會進一步加強；（4）在上市公司受到政府的紓困計畫公告日附近，公司股價會獲得正向的超額股票收益率，且在小公司中，這一關係會變得更強。結果表明資本市場對紓困計畫能夠產生積極的反應，即資本市場表明公司在收到“紓困”基金資助後，預期未來的績效能夠改善。且紓困計畫的幫扶對小公司能夠產生更強的影響。

本文的研究主要有以下可能的創新：（1）在數據方面，本文利用中國A股市場的股票質押數據有利於説明學術界增進對股權質押的認識。中國證監會要求數據的強制披露，且大股東持股比例相對較高，因此有利於清晰地研究股權質押行為；（2）在研究視角方面，本文站在了公司的融資約束角度對控股股東的股權質押動機進行探討，且深入的分析了股權質押對公司帶來的影響。此外也首次分析了政府的“紓困”計畫的效果；（3）在研究體系的系統性方面，本文的研究系統性的探討了公司大股東的股權質押的動機、對公司及資本市場的影響，有助於幫助學術界增進對控股股東的股權質押尤其是中國資本市場中的股權質押行為的理解。特別是揭露了政府在維持金融穩定與經濟穩定過程中發揮的作用，並且能夠為政府推行紓困計畫乃至解決中小民營企業融資難等問題提供一定的政策建議。整個研究實現了股權質押的閉環研究，從因何而起，帶來何種後果，到市場的反應及由此引發的政府監管力量介入紓困，再到紓困後反過來對股權質押的影響效果。

As one of financing tools, share pledging facilitates the external financing for controlling shareholders of the listed companies. Share pledging does not transfer the ownership of the shares, thus has little effect on the controlling rights of the controlling shareholders. It has since become a popular tool for the controlling shareholders to acquire external capital within the Chinese government's regulatory framework. Before 2013, China Securities Regulatory Commission (CSRC) only allowed over-the-counter share pledge. Shareholders could pledge their shares to the banks or the trust companies for financing. However, the procedures of share pledging were complicated and not facilitating. In 2013, the CSRC changed its regulation and shareholders could acquire credit from the securities companies by share pledging. In contrast to share pledging with banks, the securities companies have less information asymmetry and are more familiar with business of share pledging by the listed companies. Thus, the share pledging business experienced rapid growth since 2013. Yet in 2014 and 2015, China stock market went through dramatic transition from bull to bear market. During this period, shareholders utilized share pledging as the leverage to enlarge their profits but also losses. This led to higher stock market volatilities and investment risk. When the fall of stock price triggered a margin call, the pledged shares would be forced to sell off if shareholders could not meet the margin requirements, leading to worse price crash. The stock market was deteriorated by the fact that most controlling shareholders of the listed companies engaged in share pledging financing. By the end of 2017, some controlling shareholders even pledged all their shares. To alleviate the risk on the stability of stock market, Chinese government implemented a series of bail-out plans, which were called 'Shu Kun' plans in Chinese.

As one of financing tools, share pledging provides more financing options for listed companies as well as investors. In the meantime, such financing also has negative effects. Share pledging financing has attracted increased attentions from the academia and the industry. What are the motivations for controlling shareholders to pledge their shares? What are the effects of share pledging on the firm's operating and stock performance? How does share pledging affect the stock price volatility? What are the real effects of the bail-out plans? Existing studies have not tackled these questions yet. With this background, this thesis systematically investigates the share pledging financing based on Chinese listed companies.

This thesis uses Chinese A-share listed companies from 2003 to 2018 as the sample for empirical studies. Firstly, this thesis investigates the motivation of controlling shareholders to pledge shares for external financing. More specifically, this study focuses on the financial constraints of the firms and examines their impacts on share pledging financing. Secondly, this thesis discusses the economic consequences of controlling shareholders' share pledging and studies the relationship between the level of share pledging and the operating and stock performance of the listed companies. In addition, this study investigates the impact of share pledging on the stock price volatility and further discusses this relationship in the bear market context. Lastly, this thesis analyzes the stock price response to the 'bail-out' packages from the government when the listed companies accept them.

The conclusions of this thesis include: (1) Controlling shareholders of the firms with heavy financial constraints are more likely to engage in share pledging financing. This study finds that one essential motivation for share pledging financing of controlling shareholders is to maximize their own benefits instead of the company's welfare. (2) The level of share pledging tends to be negatively related with the operating and stock performance of the listed firm in the next financial year. The result shows that share pledging of the controlling shareholders has detrimental impacts on firm's performance. A major motivation for controlling shareholders to pledge shares is to expropriate the minority shareholders. (3) The controlling shareholders' share pledging could enhance the stock price volatility and this relationship is more distinct in the bear market. (4) Investors could earn positive abnormal returns on the announcement date when a firm obtains the 'bail-out' package, and the positive abnormal returns are higher for the small firms. The result illustrates that capital market are positively affected by the government's 'bail-out' package, particularly for the small firms.

The contributions of this thesis are as follows: (1) This thesis employs large sample study using the share pledging data in China where the listed companies of the controlling shareholders are required to disclose share pledging information. This contributes to in-depth understanding of share pledging financing. (2) This study investigates the motivations of controlling shareholders' share pledging under financial constraints and discusses the economic consequence of share pledging on the operating and stock performance of the listed companies. In addition, this paper evaluates the effect of 'bail-out' policy and reveals that the government plays a crucial role in maintaining the stability of the stock market. (3) This thesis systematically discusses the motivation of share pledging of the controlling shareholders of the company, share pledging's impact on the company and the stock price. It contributes to in-depth investigations from a variety of the perspectives on the controlling shareholders' share pledging, particularly the share pledging behaviors in the Chinese stock market. Furthermore, this thesis shows the important role of the government in maintaining the overall financial and economic stability. It also based on empirical evidence provides policy advice for the government to implement the bail-out plan and to help alleviate the difficult financing situations of small and medium private enterprises. The thesis provides systematic study of share pledging, investigates its motivations, its market reactions and the government's bail-out packages and their effect on stock price.