try this
assumed Col A has cusip
Col B has amount
in Cell C2 put this formula and drag it down

=IF(A2=A3,"",SUMIF($A$2:$A$100,A2,$B$2:$B$100))



On Nov 17, 10:42*pm, novice wrote:
trying to write a formula that adds values in one column if another column
contains like values (cusip)

can't do sumif because the value changes every 2 - 10 cells or so and there
are 1400 lines in spreadsheet and about 300 cusips

I want it sum by cusip. *I know there's a simple way but I've exhausted my
search.

example

cusip * * * * * * *amt * sum by cusip
912810FE3 *300
912810FE3 *500 * *800
912803BL6 *100
912803BL6 *200
912803BL6 *300 * *600