Can one PERMNO have multiple CRSP_COMPANY_KEYs?

Yes. For equities that are included in CRSP Stock Database, a new CRSP_COMPANY_KEY is assigned to the security whenever the name, ticker, or cusip changes. The PERMNO and PERMCO in the records will remain the same.

For example, Red Hat, Inc. changed the ticker from RHAT to RHT. Therefore, a new CRSP_COMPANY_KEY (11555) was assigned. In this case, PERMNO 87184 are associated with two CRSP_COMPANY_KEYs, 11554 and 11555.

Below is the name event history for PERMNO 87184 in CRSP Stock Database.

 Namedt    Enddt NCUSIP   Ticker Company Name      SH EX  SIC
19990811 20000731 75657710 RHAT   RED HAT INC      11  3 7370
20000801 20010823 75657710 RHAT   RED HAT INC      11  3 7372
20010824 20060713 75657710 RHAT   RED HAT INC      11  3 7372
20060714 20061211 75657710 RHAT   RED HAT INC      11  3 7372
20061212 20081128 75657710 RHT    RED HAT INC      11  1 7372

 

Below are the CRSP_COMPANY_KEYs associated with PERMNO 87184.

crsp_company_key	security_name	cusip	permno	permco	ticker
11554	RED HAT INC	75657710	87184	16753	RHAT
11555	RED HAT INC	75657710	87184	16753	RHT