Knowledge Base

Citigroup volume has missing values for four dates

There are four dates where the daily trading volume for Citigroup, PERMNO 70519, Ticker C, exceeds our database’s

as -99 (missing). The true trading volume values for those dates:

How can a security have a negative dividend amount?

There are four PERMNOs in the CRSP security universe with negative dividend amounts. In the 1920s, some companies

CRSP that they reference SEC documents as SIC code sources.

assigned or reviewed with a strict procedure by any government agency, most large companies belong in multiple SIC codes,

and they change over time. After the initial SIC code assignment when a company goes public, no government agency ever

looks at that code or the company again—quite often a company reports its initial SIC code forever. There are cases in which

companies would have obsolete SIC codes from the 1972-coding scheme in their SEC filings from the early 1990s.

The U.S. Department of Labor provides information on the 1987 SIC coding scheme at

http://www.osha.gov/oshstats/sicser.html.

Why does the history for PowerShares QQQ Trust only extend to April 12, 2007?

identifiers, PERMCO. Thus, PowerShares QQQ cannot maintain the same security level identifier as the NASDAQ 100

• To merge the return histories of both securities replace the initial null value for PowerShares QQQ Trust with the

delisting return of the NASDAQ 100 Trust Series I.

In researching the bid and ask quotes, CRSP found a number of questionable data points. Registered market makers, usually

off the primary listed exchange, periodically posted noncompetitive quotes that were captured as the closing bid and ask.

These quotes had wide spreads, not typical of the day's trading activity. In many cases, spreads were intentionally set as wide

Example:

This security ceased trading on NASDAQ on June 16, 1999. It resumed trading on NASDAQ on June 12, 2000. The interval

between these dates is represented by a name line with Exchange Code set to zero, and the Ticker field blank.

Example:

This security ceased trading on NASDAQ on June 16, 1999. It resumed trading on NASDAQ on June 12, 2000. The interval

between these dates is represented by a name line with Exchange Code set to zero, and the Ticker field blank.

Securities trade on a when-issued basis when officially they have yet to be issued, but they trade as if they have been. These

during the same time that the rest of its shares trade regular way, with the entitlement to the distribution

The CUSIP number consists of nine characters. The first six characters uniquely identify the issuer and have been assigned to

There is only one known case, PepsiAmericas in 2000 and 2001, when this occurred. CRSP's name history for a security tracks

changes in its CUSIP number, accessible by the unique identifier, PERMNO. On CRSP, a PERMNO can be associated with

An investment bank will buy shares of a non-US-traded stock in a foreign market and issue ADR shares on the US

market. A depository bank handles the issuance and cancellation of ADR certificates.

The depositary bank sets the ratio of US ADRs per home country share. This ratio can be less than or greater than 1 in

order to get the ADR in a comparable trading range with US equities. CRSP does not have a variable for the ratio of

The following sharecodes are maintained internally by CRSP, but are excluded from the subscriber version of the CRSP

database:

NASDAQ for coverage in the stock database.

Why are there Closing Bids that are greater than or equal to Closing A

sks in the CRSP Stock Database?

Maker is the same or lower that the Bid price of another Market Maker. Though it is an unusual condition, it does occur in fast-