Program Trading Averaged 70.5 Percent of NYSE Volume during June 21-25 http://www.nyse.com/press/1088675982795.html
交易策略各种类型的比例： index arbitrage: 4.8% derivative product-related strategies (besides index arbitrage) that are subject to Rule 80A: 0.1% customer facilitations（客户便利）, index substitutions（指数置换）, liquidation of error accounts（错误帐户的清算）, risk modifications/hedge（风险的减小或对冲）, and liquidation of exchange-for-physicals stock positions（期货换现货的股票头寸的清算）, etc.: 95.2%