When you download data from WRDS to an Excel spreadsheet and include CUSIPs in your file, you often have CUSIPs that that look weird. See this example from CompuStat North America Index Constituents, the column Company Cusip should contain 9-digit CUSIPs: 207 more words
Using CUSIP codes can cause headaches in Excel. They can be confused with numbers expressed in scientific format or leading zeroes can be lost. The blog post below, written by EDSC, offers some assistance on the subject.