2011 E-mail: yoshihiko.sugihara@boj.or.jp / /2012.1 227 1. 1 2 3 4 5 smart order routing: SOR 6 1 2 2011 4 3 2011 3 5 4 5 2011 3 7 6 SOR 2011 4 5 228 /2012.1 2011 2. 1 1 1 229 1 1 3 4 5 2 1970 2 1970 i ii iii i 1990 i-a i-b 2000 i iii i-a i-b ii iii 230 /2012.1 2 3 2 231 . 3 7 . 2 8 9 10 11 3 7 2011 2 8 Konishi [2002] McCulloch and Kazakov [2007] Bouchard, Dang, and Lehalle [2009] 9 2011 3 4 10 20