Proceedings of 9th International Business and Social Science Research Conference 6 - 8 January, 2014, Novotel World Trade Centre, Dubai, UAE, ISBN: 978-1-922069-41-2 Securities Transaction Tax and Market Quality: The Case of France Peter Gomber, Martin Haferkorn and Kai Zimmermann1 We study the French Securities Transaction Tax implementation of August st 1 , 2012. Although a similar tax is planned to be introduced across 11 European countries, consequences for market quality are yet to be thoroughly assessed. We show that liquidity demand and supply significantly drop. Even though the French proposal exempts professional liquidity provision, we find increased spreads and a declined order book depth resulting in additional transaction costs for market participants besides the tax. As all venues trading French stocks are affected, we further find that STT threatens inter-market information transmission by impairing price coordination among fragmented markets in Europe. 1 Chair of e-Finance, Goethe University, Frankfurt Faculty of Economics and Business Administration, Grüneburgweg 1, 60323 Frankfurt am Main, Germany, Tel: +49 (69) 798-34683/33872/33857, Fax: +49 (69) 798-35007, Email: Gomber @wiwi.uni-frankfurt.de