RT Journal Article SR Electronic T1 Fragmentation and Price Discovery: A Comparison of Reg NMS and MiFID1 JF The Journal of Trading FD Institutional Investor Journals SP 6 OP 36 DO 10.3905/jot.2014.9.4.006 VO 9 IS 4 A1 Frederick H. deB. Harris A1 Thomas H. McInish A1 Frank J. Sensenbrenner A1 Robert A. Wood YR 2014 UL https://pm-research.com/content/9/4/6.abstract AB We study NYSE, NASDAQ, and ARCA prices for DJIA stocks and LSE, Xetra, and Chi-X prices for five leading British equities. MiFID1 hastened fragmentation but accomplished the intended cointegration of European equity markets that had previously been segmented. Initially, price discovery in London was largely unaffected; permanent quote innovations remained more than 90% attributable to the LSE. However, clearing and settlement fee reductions by Chi-X five months later did result in a substantial reduction in the information impounding and price discovery efficiency of London Stock Exchange trades. The contemporaneous situation in the United States with the implementation of Reg NMS was quite different. During its staggered rollout in 2007, NYSE’s price discovery declined steadily from 74% to 41%, with much of that role migrating to ARCA. In this case, the price discovery efficiency of NASDAQ substantially improved.TOPICS: Exchanges/markets/clearinghouses, security analysis and valuation, developed