Hi!

I tried to collapse the following data but it says varlist required, why?

collapse smi1 smi2 lsmi1 lsmi2 [pw==shares], by (permno date)

Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input double(permno shares date smi1 smi2) float(lsmi1 lsmi2)
10001 119324 18628        -69.55078125 -1260000   -736.769 -2210000
10001 117181 18628                   0        0  -51.88709  -940000
10001  16900 18628                   0        0 -126.95777 -2300000
10001   6150 18628   87.21446990966797  1580000          0        0
10001  12366 18628                   0        0   998.0674  5500000
10001  24315 18628  240.66776084899902  4360000   635.3408 11510000
10001    750 18628  165.04510498046875  2990000  -165.0451 -2990000
10001  19986 18628   51.33509826660156   930000  103.22218  1870000
10001 190860 18628   35.87936782836914   650000          0        0
10001  58062 18628  -160.0771942138672 -2900000  -204.2364 -3700000
10001  24315 18629  -2143.792381286621 -9550000   807.5618 14630000
10001  58062 18629   1033.946834564209  4500000  -364.3136 -6600000
10001 190860 18629  -792.1060791015625 -2800000  35.879368   650000
10001   6150 18629  -87.21446990966797 -1580000          0        0
10001  16900 18629  -750.0168380737305  -800000          0        0
10001 117181 18629   620.0230731964111  2570000  -51.88709  -940000
10001    750 18629 -1810.5282592773437 -6400000   165.0451  2990000
10001  19986 18629 -1314.4269104003906 -6900000   205.8924  3730000
10001 119324 18629    736.769063949585  2210000  -763.8166 -2700000
10001  12366 18629   818.6706085205078  2250000   906.9891  3850000
10001 117181 18630                   0        0   594.0795  2100000
10001  19986 18630  -205.8923797607422 -3730000  -902.6422   560000
10001 190860 18630                   0        0  -720.3474 -1500000
10001  16900 18630  126.95777130126953  2300000  -750.0168  -800000
10001  24315 18630 -24.287572860717773  -440000 -1557.0267  1080000
10001  58062 18630 -57.958980560302734 -1050000   771.7514  -250000
10001   6150 18630                   0        0  -87.21447 -1580000
10001 119324 18630         69.55078125  1260000    736.769  2210000
10001    750 18630  221.34811401367187  4010000  -1645.483 -3410000
10001  12366 18630   91.07839965820313  1650000   818.6706  2250000
10001  19986 18631                   0        0  -205.8924 -3730000
10001  24315 18631 -195.40457344055176 -3540000  -24.28757  -440000
10001  16900 18631                   0        0  126.95777  2300000
10001   6150 18631   87.21446990966797  1580000          0        0
10001  12366 18631                   0        0    91.0784  1650000
10001    750 18631                   0        0   221.3481  4010000
10001 117181 18631                   0        0          0        0
10001 119324 18631  -27.04752540588379  -490000   69.55078  1260000
10001  58062 18631  -160.0771942138672 -2900000  -57.95898 -1050000
10001 190860 18631                   0        0          0        0
10001 117181 18632                   0        0          0        0
10001  58062 18632  218.03617477416992  3950000  -160.0772 -2900000
10001  12366 18632  -91.07839965820313 -1650000          0        0
10001 190860 18632  -35.87936782836914  -650000          0        0
10001    750 18632  -193.1966094970703 -3500000          0        0
10001   6150 18632                   0        0   87.21447  1580000
10001  24315 18632 -215.27620697021484 -3900000 -195.40457 -3540000
10001  16900 18632  126.95777130126953  2300000          0        0
10001  19986 18632 -154.55728149414062 -2800000          0        0
10001 119324 18632         69.55078125  1260000 -27.047525  -490000
10001 119324 18633  -27.04752540588379  -490000   69.55078  1260000
10001 117181 18633  25.943544387817383   470000          0        0
10001  16900 18633                   0        0  126.95777  2300000
10001  24315 18633   49.67912673950195   900000  -215.2762 -3900000
10001 190860 18633   35.87936782836914   650000 -35.879368  -650000
10001  19986 18633   51.33509826660156   930000  -154.5573 -2800000
10001   6150 18633  -87.21446990966797 -1580000          0        0
10001    750 18633  28.151504516601563   510000  -193.1966 -3500000
10001  12366 18633  -44.15922546386719  -800000   -91.0784 -1650000
10001  58062 18633                   0        0   218.0362  3950000
10001  16900 18634  126.95777130126953  2300000          0        0
10001  19986 18634 -154.55728149414062 -2800000    51.3351   930000
10001  12366 18634  -91.07839965820313 -1650000  -44.15923  -800000
10001 119324 18634         69.55078125  1260000 -27.047525  -490000
10001  58062 18634  102.11821365356445  1850000          0        0
10001  24315 18634 -176.63690948486328 -3200000   49.67913   900000
10001 190860 18634                   0        0  35.879368   650000
10001   6150 18634                   0        0  -87.21447 -1580000
10001 117181 18634                   0        0  25.943544   470000
10001    750 18634  -193.1966094970703 -3500000  28.151505   510000
48486   157100 18630                   0        0 -179.94884 -3260000
48486   114744 18630                   0        0   828.6754  6020000
48486       30 18630                   0        0  -875.7326 -4480000
48486   206461 18630  126.95777130126953  2300000  -750.0168  -800000
48486   735988 18630   44.71121597290039   810000  121.98987  2210000
48486   141006 18630                   0        0  -74.51869 -1350000
48486  6032435 18630   68.99878692626953  1250000   678.9481  2400000
48486    93037 18630   70.10276794433594  1270000  -508.5901 -1170000
48486   134071 18630                   0        0   560.7532  1290000
48486   224297 18630         69.55078125  1260000    736.769  2210000
48486    96331 18630                   0        0  1007.1063  4220000
48486   340026 18630                   0        0  -176.6369 -3200000
48486  2843432 18630   91.07839965820313  1650000   818.6706  2250000
48486     8832 18630                   0        0  565.79004  2000000
48486  1996036 18630                   0        0  -720.3474 -1500000
48486   471167 18630                   0        0 -17.663689  -320000
48486   107866 18630                   0        0   594.0795  2100000
48486   341814 18630                   0        0  -786.4482 -2780000
48486 37259331 18630 -24.287572860717773  -440000 -1557.0267  1080000
48486   205836 18630                   0        0  -704.4086 -2490000
48486  2538329 18630  221.34811401367187  4010000  -1645.483 -3410000
48486   494176 18630                   0        0  -87.21447 -1580000
48486 21538876 18630  -205.8923797607422 -3730000  -902.6422   560000
48486   603629 18630                   0        0  -672.0482 -3100000
48486    13728 18630                   0        0 -1402.4695 -2720000
48486    78400 18630                   0        0          0        0
48486  1629980 18630                   0        0  -777.9614 -2750000
48486   667007 18630    80.0385971069336  1450000  185.46873  3360000
48486  2407336 18630 -57.958980560302734 -1050000   771.7514  -250000
48486  6905562 18630                   0        0          0        0
48486   341814 18631                   0        0          0        0
48486    96331 18631  40.295291900634766   730000          0        0
48486 37259331 18631 -195.40457344055176 -3540000  -24.28757  -440000
48486 21538876 18631                   0        0  -205.8924 -3730000
48486       30 18631  -71.75873565673828 -1300000          0        0
48486    93037 18631  27.047523498535156   490000   70.10277  1270000
48486  2843432 18631                   0        0    91.0784  1650000
end
format %td date
Thanks!