There are several reasons why data on our site may be different from data from other sources. Here are some of the most common reasons:
We adjust our historical price data to remove the effects of fund distributions, dividends, and stock splits from our charts. If you are noticing multiple data differences for a stock's historical data, this is most likely the reason.
Splits, distributions, and dividends are “artificial” changes in the price of a ticker symbol that create gaps on technical charts causing misleading signals from technical indicators. To eliminate those gaps, we decrease our historical prices (and increase our historical volume data) in a way that removes these misleading signals.
For more information about our data adjustment policy, please see this article:
Historical Price Data is Adjusted for Splits, Dividends and Distributions
In addition, we now offer special unadjusted ticker symbols for most stocks and ETFs. To see a chart of unadjusted data, just add an underscore character to the front of the stock's normal symbol.
When the markets are open, users who don't have an “official” real-time data plan for the US will see real-time data from the BATS exchange. BATS data is very similar, but not identical, to data from the NYSE and Nasdaq exchanges. For example, the volume data for BATS quotes is always much lower. For more information on the differences between BATS data and official NYSE/Nasdaq data, please see this article:
How do your BATS real-time charts work?
We provide real-time data on our charts as quickly as we receive it from our datafeed. That said, it is still possible that someone with a professional datafeed may see real-time data on those feeds sooner than it appears on our charts. That delay should only be a couple of seconds at most, however.
Our International Indexes are only updated once per day, typically around the end of the US trading day. That may be several hours after the exchange in question has closed for the day. We provide International Indexes in order to help our users gain a long-term understanding of the direction of those markets. Our International Indexes are not intended for active traders in those markets.
We also recommend that people use the large collection of International ETFs that are now available as real-time proxies for tracking international markets.