The CSI Data Release Schedule and Posting Status screen on the website show Preliminary Stock Data available at 4:45 p.m. Clearly, the CSI computers and database staff would not have had time to screen and certify the massive stock database in this brief interval between the close of the markets and this release time. This early posting time is possible only because preliminary data is posted without prior screening, with the intent that it will be considered conditional data until confirmed through the official update around 7 p.m.
This represents a recent departure from CSI's longstanding policy of posting only finalized quotes, as opposed to preliminary price data that would be comparable to the early quotes provided by other services. Because of customer demand for early reports, CSI now offers preliminary data as described here. We do so with the caveat that customers should act only on the official data that will become available around 7:00 p.m. daily.
The preliminary data will be revised in subsequent updates whenever necessary through an existing utility that allows Unfair Advantage users to call for data as frequently as desired, so long as each call comes from the same computer. This means that you may call two or more times every evening without paying extra fees. The first call would allow you to prepare for the next day's trading with preliminary stock data, and subsequent calls would fill in any missing or flawed entries that may have resulted from that early or preliminary update.
Even with preliminary updates, a nearly flawless historical database is assured once our data checking efforts are complete. Even if an update were not made after the final posting, the following day's update would correct missing or flawed data from an early update on the previous day. Customers are warned that there is a strong likelihood that some preliminary stock reports will be revised. No trade orders should be placed without confirmation of the "official" quote after the official release time and without confirmation from your broker.
In deciding whether or not to use preliminary data, you should ask yourself if you wish to receive possibly flawed preliminary data in order to process earlier updates. In other words, is expediency at the cost of possible inaccuracy (as practiced by our competitors who follow an early release schedule) a desirable tradeoff? If your answer is "no" to these questions, then simply ignore the early stock quotes and be sure to update again after the official release time or the following day to receive verified stock data. If you feel that a greater possibility of errors is acceptable, provided they are supplied with the understanding that corrections would be available through subsequent updates, then feel free to indulge in the preliminary stock data. Only CSI gives you the benefit of early access to preliminary data plus the assurance of an accurate database through automatic revisions.