We review the extensive literature on systemic risk and connect it to the current regulatory debate. While we take stock of the achievements of this rapidly growing field, we identify a gap between two main approaches. The first one studies different sources of systemic risk in isolation, uses confidential data, and inspires targeted but complex regulatory tools. The second approach uses market data to produce global measures which are not directly connected to any particular theory, but could support a more efficient regulation. Bridging this gap will require encompassing theoretical models and improved data disclosure

Standard-Nutzungsbedingungen:Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden.Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen.Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. Terms of use: Documents in EconStor may be saved and copied for your personal and scholarly purposes.You are not to copy documents for public or commercial purposes, to exhibit the documents publicly, to make them publicly available on the internet, or to distribute or otherwise use the documents in public. licence. www.econstor.eu If the documents have been made available under an Open Content Licence (especially Creative Commons Licences), you may exercise further usage rights as specified in the indicated Working Paper SeriesFinancial transaction taxes, market composition, and liquidity Jean-Edouard Colliard, Peter HoffmannDisclaimer: This paper should not be reported as representing the views of the European Central Bank (ECB). The views expressed are those of the authors and do not necessarily reflect those of the ECB. No 2030 / February 2017 ABSTRACTWe use the introduction of a financial transaction tax (FTT) in France in 2012 to test competing theories on its impact. We find no support for the idea that an FTT improves market quality by affecting the composition of trading volume. Instead, our results are in line with the hypothesis that a lower trading volume reduces liquidity, and thereby market quality. Consistent with theories of asset pricing under transaction costs, we document a shift in security holdings from short-term to long-term investors. Finally, our findings show that moderate aggregate effects on market quality can mask large adjustments made by individual agents. Non-technical summaryThis paper empirically examines the 2012 introduction of a financial transaction tax (FTT) on equity trading in France. We motivate our analysis by contrasting two opposing strands of theoretical literature that make opposing predictions on the impact of such as policy. Models based on "composition effects"suggest that FTTs will primarily affect agents that are the source of excessive stock price volatility (socalled noise traders), and thus improve market quality. However, other researchers question the relevance of this channel and instead highlight a "liquidity effect" with opposing consequences. They argue that reduced market participation lowers liquidity, which makes markets more volatile and prices less efficient as arbitrageurs face higher costs for correcting price dislocations.Our empirical analysis shows that, following the policy change, average trading volume decreased by around 10%, and this development was accompanied by a moderate ...

We review the extensive literature on systemic risk and connect it to the current regulatory debate. While we take stock of the achievements of this rapidly growing field, we identify a gap between two main approaches. The first one studies different sources of systemic risk in isolation, uses confidential data, and inspires targeted but complex regulatory tools. The second approach uses market data to produce global measures which are not directly connected to any particular theory, but could support a more efficient regulation. Bridging this gap will require encompassing theoretical models and improved data disclosure.

Common wisdom has it that competition between trading platforms in securities markets benefits investors because it forces platforms to charge smaller fees. We challenge this view by showing that a decrease in trading fees can impair investors' expected welfare in limit order markets. Indeed, a decrease in trading fees can induce investors to strategically post limit orders with a smaller execution probability, in order to earn a greater surplus in case of execution. Hence, a decrease in trading fees yields larger gains from trade when a trade takes place but it can reduce the likelihood of a trade in the first place. The model has testable implications for the effects of a change in trading fees and their breakdown between investors submitting limit orders (makers) and market orders (takers) on limit order fill rates and various measures of bid-ask spreads.

Common wisdom has it that competition between trading platforms in securities markets benefits investors because it forces platforms to charge smaller fees. We challenge this view by showing that a decrease in trading fees can impair investors' expected welfare in limit order markets. Indeed, a decrease in trading fees can induce investors to strategically post limit orders with a smaller execution probability, in order to earn a greater surplus in case of execution. Hence, a decrease in trading fees yields larger gains from trade when a trade takes place but it can reduce the likelihood of a trade in the first place. The model has testable implications for the effects of a change in trading fees and their breakdown between investors submitting limit orders (makers) and market orders (takers) on limit order fill rates and various measures of bid-ask spreads.