Assuming you have CUSIP in Col A and amount in Col B with header rows

IMP: Change 1500 in all formulas to the last row containing your data

1. Enter this in D2
=COUNTIF(A2:$A$1500,A2)
and copy down till end of your data

2. Filter your data on Col D equal to 1

3. Enter this in the first row (AND change 2 in A2 to the first row in the
filter)
=SUMPRODUCT(--($A$1:$A$1500=A2),$B$1:$B$1500)
Copy this formula to the filtered rows

4. Remove filter, you should have the formula above in rows with 1 in Col D

5. Delete Col D and you are done
"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