In an ideal world, it would be volume times vwap. In a less ideal world, you can estimate vwap as avg(open + close + avg(high, low)) assuming this is for the US stocks.
Thx Sle. So seems I can't download turnover directly. Actually what I want is sth like vwap but first I need turnover.....
Bats explanation "Notional Value", which is also referred to as "Dollar Value Traded", is calculated by multiplying the execution price of each transaction by the total number of shares executed in each transaction. This method of calculating market share, as opposed to simply using the total number of shares that traded hands, can be a better representation of the actual "size" of a market. The larger the Notional Value traded, the more risk that actually changed hands. By way of example, 100 shares of stock ABC at $362 per share is a much larger transaction than 100 shares of stock XYZ at $2.20 a share. Other assets classes, such as futures and options, and most other equity markets outside of the U.S., historically have used Notional Value as an index into how much activity takes place on those markets. Bats is the first to offer a real-time view, market-wide, into Notional Value traded in the U.S. cash equity markets.