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Merge Compustat and CRSP

Using the CRSP/Compustat Merged Database (CCM) to extract data is one of the fundamental steps in most finance studies. Here I document several SAS programs for annual, quarterly and monthly data, inspired by and adapted from several examples from the WRDS.1

First, we need to create a GVKEY-PERMNO link table.

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%let beg_yr = 2000;
%let end_yr = 2003;

proc sql;
create table lnk as
select *
from crsp.ccmxpf_lnkhist
where
    /* See below for a description of the link types */
    linktype in ("LU", "LC") and
    /* Extend the period to deal with fiscal year issues */
    /* Note that the ".B" and ".E" missing value codes represent the   */
    /* earliest possible beginning date and latest possible end date   */
    /* of the Link Date range, respectively.                           */
    (&end_yr+1 >= year(linkdt) or linkdt = .B) and 
    (&beg_yr-1 <= year(linkenddt) or linkenddt = .E)
order by 
    gvkey, linkdt;
quit;
Link Type Description
LC Link research complete (after extensive research by CRSP). Standard connection between databases.
LU Link is unresearched by CRSP. It is established by comparing the Compustat and historical CRSP CUSIPs. LU represents the most popular link type.
LS Link valid for this security only.2
LX Link to a security that trades on foreign exchange not included in CRSP data.
LD Duplicate link to a security. Two GVKEYs map to a single PERMNO (PERMCO) during the same period, and this link should not be used. Almost all of these cases happened before 1990.
LN Primary link exists but Compustat does not have prices.3
NR No link available; confirmed by research.
NU No link available; not yet confirmed.

According to WRDS's support page:

  • Primary link types (LC, LU and LS) account for 41% of the links in CCM.
  • Secondary link types (LX, LD and LN) account for only 2%.
  • Non-matching link types (NR and NU) account for the rest 57%, which is expected because of the different coverage of the two databases.

Generally, using LC and LU should be sufficient.

Compustat Annual and CRSP

Example ccmfunda.sas.

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proc sql;
create table mydata as 
select *
from lnk, comp.funda (keep=gvkey fyear datadate indfmt datafmt popsrc consol sale) as cst
where indfmt= 'INDL' 
and datafmt='STD' 
and popsrc='D' 
and consol='C' 
and lnk.gvkey = cst.gvkey
and (&beg_yr <= fyear <= &end_yr) 
and (linkdt <= cst.datadate or linkdt = .B) 
and (cst.datadate <= linkenddt or linkenddt = .E);
quit;

Compustat Quarterly and CRSP

Example ccmfundq.sas.

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proc sql;
create table mydata as 
select *
from lnk, comp.fundq (keep=gvkey fyearq datadate indfmt datafmt popsrc consol saley saleq) as cst
where indfmt= 'INDL' 
and datafmt='STD' 
and popsrc='D' 
and consol='C' 
and lnk.gvkey = cst.gvkey
and (&beg_yr <= fyearq <= &end_yr) 
and (linkdt <= cst.datadate or linkdt = .B) 
and (cst.datadate <= linkenddt or linkenddt = .E);
quit;

Compustat Monthly and CRSP

To be done.

  1. WRDS Overview of CRSP/COMPUSTAT Merged:
    https://wrds-www.wharton.upenn.edu/pages/support/manuals-and-overviews/crsp/crspcompustat-merged-ccm/wrds-overview-crspcompustat-merged-ccm/
    Use CRSP-Compustat Merged Table to Add Permno to Compustat Data:
    https://wrds-www.wharton.upenn.edu/pages/support/research-wrds/macros/wrds-macro-ccm/
    Merging CRSP and Compustat Data:
    https://wrds-www.wharton.upenn.edu/pages/support/applications/linking-databases/linking-crsp-and-compustat/ ↩

  2. Other CRSP PERMNOs with the same PERMCO will link to other GVKEYs. LS links mainly relate to ETFs where a single CRSP PERMCO links to multiple Compustat GVKEYs. In Compustat, even though they may belong to the same investment company (e.g. ISHARES), ETFs are presented with different GVKEYs and CRSP flags this situation. ↩

  3. Prices are used to check the accuracy of the link. For linktype LN there is no price information available even on a quarterly or annual basis. The user will have to decide whether or not to include these links. ↩

Last update: May 25, 2020

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