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US Market Data
- Overview
- Layout & Security Types
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- Historical Database
> Database Maintenance
- Custom Folders

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DATABASE MAINTENANCE

Premium Data maintains your US database regularly in order for you to have an accurate record of currently trading securities.  Maintenance is performed on a daily basis.

The following actions are performed as part of daily database maintenance:

  • Equity prices are adjusted for changes to a company's capital base (such as share splits, consolidations, or capital restructures)
  • De-listed securities and associated trading instruments are moved from the main database into a "De-listed Securities" folder (from where you may delete them at your leisure)
  • Securities that have undergone a name or code change are refreshed to reflect the new name or code.
  • New securities that have been added to the database are assigned their full names.
     
  • Securities that have changed their exchange listing (eg. from NASDAQ to NYSE) are automatically transferred with full trading history intact.

WARNING:  Most free sources of data do not perform any maintenance -  they simply provide flat ASCII or CSV text files each day with no corporate action information.

Why is this important?

If you are a treating the market as a professional trader would, you need to have an up-to-date and consistent database.  You want to spent your time analysing stocks not processing routine, mundane corporate actions.

Can't I just use free data and do the maintenance myself?

We wish you luck if you do.    We wouldn't want to do these manually each day/week/month and highly recommend you use a service like Premium Data to do all this hard work for you. Why spend all your time maintaining your database when you should be looking for trading opportunities? Here is a report of the amount of corporate actions that we process each year:

  Average Maintenance Actions Per Year
Exchange Capital Adjustments (eg splits, consolidations) Company Name Change Symbol / Company Name Change Symbol / Company Name
& Exchange Change
Delisting
AMEX 18 114 30 30 84
NASDAQ 342 168 600 432 342
NYSE 210 492 66 96 96
OTC 360 450 6228 60 456
TOTAL 930 1224 6924 618 978

Why is it important to have OTC stocks in my database?

Many companies that temporarily fail listing rules on the other exchanges (AMEX, NASDAQ, NYSE) often sit in the OTC-BB market until they can rectify the issue.  If you do not maintain an OTC-BB history, when this stock subsequently relists on a major exchange you will be without any trading history. OTC stocks are still quite tradeable.