placement numbers (PPNs) used by the insurance industry. The 9th digit is an automatically generated check digit using the "Modulus 10 Double Add Double" technique based on the Luhn algorithm. To calculate the check digit every second digit is multiplied by two. Letters are converted to numbers based on their ordinal position in the alphabet, starting with A equal to 10. TBA CUSIP format There is a special assignment of CUSIP numbers for TBA Security. Working with the MBSCC, CUSIP Global Services (CGS) developed a specialized identification scheme for TBA (To Be Announced) mortgage-backed securities. TBA CUSIPs incorporate, within the identifier itself, a security’s mortgage type (Ginnie Mae, Fannie Mae, Freddie Mac), coupon, maturity and settlement month. TBA Algorithm: Position 1–2: Product Code (e.g., single-family mortgage, ARM, Balloon, etc.) Position 3: Type of Mortgage (Ginnie Mae, Fannie Mae, Freddie Mac) Position 4–6: Coupon Position 7: Maturity Position 8: Settlement Month Position 9: Check Digit The exact values for each position are available in a spreadsheet called the TBA Grid. Check digit lookup table The values below are summed for the first 8 characters, then reduced to 1 digit by : Check digit pseudocode algorithm Cusip-Check-Digit is input: cusip, an 8-character CUSIP. sum := 0 for 0 ≤ i < 8 do c := the ith character of cusip if c is a digit then v := numeric value of the digit c else if c is a letter then p := ordinal position of c in the alphabet (A=1, B=2...) v := p + 9 else if c = "*" then v := 36 else if c = "@" then v := 37 else if c = "#" then v := 38 end if if 7 - i is even then v := v × 2 end if sum := sum + int(v div 10) + v mod 10 repeat return (10 - (sum mod 10)) mod 10 Examples Apple Inc.: 037833100 Cisco Systems: 17275R102 Google Inc.: 38259P508 Microsoft Corporation: 594918104 Oracle Corporation: 68389X105 3½% Treasury Gilt 2068: EJ712548 See also Central Index Key ISO 6166 ISO 10383 ISO 10962 Option symbol SEDOL Sicovam Ticker symbol References External links CUSIP Global Services Website TBA CUSIP Calculator American Bankers Association Financial metadata Market data Security identifier types Unique identifiers