9月20日大成交量因option到期
Volume: The trading volume swelled both in the NYSE and NASDAQ stock exchanges and came in heavier than yesterday’s level. The heavy volume trading coupled with over -0.2% losses, resulted in a distribution day for all three indexes. The heavy volume trading partially due to the option expiration.
Check this out
http://volumewatchers.com/stock-market-analysis/09-20-2013-dow-jones-distributes-hard-nasdaq/
Option Calendar:
http://www.marketwatch.com/optionscenter/calendar