There should be information about the variables (such as mktrf, smb, hml, rf, umd) from datasets ff and liq in the last year (i.e. from 201301 to 201312) for each PERMNO. Actually, I need information about the variables from datasets ff and liq for all available years for each PERMNO. Now the problem is that information about variables from datasets ff and liq for the last year of each PERMNO is missing (for other years, there is no problem). I don't know why and reckon there might be some minor mistake during the joining process.
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