CUSIP Number: Complete Guide to US Securities Identifiers

Last updated: March 2026 · 12 min read

A CUSIP number is a 9-character identifier assigned to every stock, bond, mutual fund, and other security traded in the United States and Canada. If you've ever looked at a brokerage statement or SEC filing, you've seen CUSIPs — they're the backbone of North American securities identification.

1. What Is a CUSIP Number?

CUSIP stands for Committee on Uniform Securities Identification Procedures. It's a 9-character alphanumeric code that uniquely identifies a security in the United States and Canada. The system was created in 1964 by the American Bankers Association and is now managed by CUSIP Global Services (a subsidiary of S&P Global).

Key Facts

• 9 characters — 6-char issuer code + 2-char issue number + 1 check digit
• Over 50 million CUSIPs assigned since inception
• Required by SEC, FINRA, DTCC, and virtually all US financial institutions
• Proprietary — owned by the American Bankers Association, licensed through S&P Global
• Covers stocks, bonds, mutual funds, ETFs, government securities, money market instruments

2. CUSIP Structure (9-Character Breakdown)

CUSIP:   0 3 7 8 3 3 1 0 0
         ─────────── ───── ─
              │         │   │
              │         │   └─ Check digit (1 char)
              │         │      Validates the CUSIP
              │         │
              │         └─ Issue number (2 chars)
              │            10 = common stock
              │            20-29 = preferred stock
              │            30-39 = bonds/debentures
              │            40-49 = specific issues
              │
              └─ Issuer code (6 chars)
                 Identifies the company/entity
                 037833 = Apple Inc.
                 
Example: 037833100 = Apple Inc. common stock

Issue Number Patterns

The 7th and 8th characters follow conventions (though these aren't strictly enforced):

3. Types of CUSIPs

Standard CUSIP (US Securities)

The original 9-character format for US securities. Issuer codes starting with a digit (0-9) typically represent equity issuers.

CINS (CUSIP International Numbering System)

For non-US/Canadian securities. Same 9-character format, but the first character is always a letter (A-Z) indicating the country/region:

CUSIP-6 (Issuer Only)

Sometimes you'll see just the first 6 characters used to identify an issuer (company) rather than a specific security. This is common in corporate bond databases where one issuer has dozens of bond issues.

4. How to Find a CUSIP Number

Free Methods

• Our Financial ID Translator — enter any ticker, ISIN, or company name → get CUSIP instantly
• SEC EDGAR — search company filings; CUSIPs appear in 10-K, 10-Q, and prospectus filings
• FINRA TRACE — FINRA Bond Center for corporate and municipal bonds
• Treasury Direct — treasurydirect.gov for US Treasury securities
• Your broker — all US brokers show CUSIPs on trade confirmations and account statements

Premium Sources

• CUSIP Global Services — the official source (subscription required)
• Bloomberg Terminal — type ticker → DES → CUSIP shown
• Refinitiv — full CUSIP database access

5. CUSIP to ISIN Conversion

Converting between CUSIP and ISIN is straightforward because the CUSIP is embedded inside US ISINs:

CUSIP to ISIN:
  1. Prepend "US" (or "CA" for Canadian securities)
  2. Append the CUSIP (all 9 characters)
  3. Calculate ISIN check digit (Luhn algorithm)
  
  CUSIP:  037833100
  ISIN:   US 037833100 5
          ── ───────── ─
          Country  CUSIP  Check digit

ISIN to CUSIP:
  Simply extract characters 3-11 of a US/CA ISIN.
  
  ISIN:   US0378331005
  CUSIP:    037833100  (chars 3-11)

Use our free tools for instant conversion:

• CUSIP → ISIN Converter
• ISIN → CUSIP Converter
• CUSIP → SEDOL Converter

6. CUSIP Examples

Mega-Cap US Stocks

Popular ETFs

US Treasury Securities

7. CUSIP Check Digit Algorithm

The 9th character of a CUSIP is a check digit calculated using the modified Luhn algorithm:

Example: Calculate check digit for 03783310?

Step 1: Convert letters to values
  A=10, B=11, ..., Z=35, *=36, @=37, #=38
  (All chars in this example are digits, so: 0,3,7,8,3,3,1,0)

Step 2: For even-positioned characters (2nd, 4th, 6th, 8th),
        multiply by 2:
  Pos: 1  2  3  4  5  6  7  8
       0  6  7  16 3  6  1  0
       
Step 3: If result ≥ 10, sum the digits:
       0  6  7  7  3  6  1  0 → (16→1+6=7)

Step 4: Sum all: 0+6+7+7+3+6+1+0 = 30

Step 5: Check digit = (10 - (30 mod 10)) mod 10
       = (10 - 0) mod 10 = 0

Result: 037833100 ✓

8. CUSIP vs Other Identifiers

For detailed comparisons, see our dedicated guides:

• ISIN vs CUSIP: Complete Comparison
• US Stock Identifiers (CUSIP, ISIN, FIGI, CIK)
• What Is an ISIN Number?

9. Frequently Asked Questions