Why are stock prices in the pre-market different from other platforms?
There are two reasons that the stock prices in pre-market are different:
- Data sources
The stock trading screen adopted by each trading platform may be different. Basic users can access to the pre-market prices based on Nasdaq Basic LV1 data. Users can access to complete extended market data by paying the fee in exchange for an upgrade to Nasdaq TotalView.
- Odd lots
A round lot is a standard number of securities to be traded on an exchange. In stocks, a round lot is considered 100 shares or a larger number that can be evenly divided by 100. However, an odd lot is an order amount for a security that is less than the normal unit of trading for that particular asset. So the transactions of odd lots are not calculated for pre-market and after-market prices.