Adding column with header to pipe-delimited file using awk or sed

Question

I am trying to add a column with a header "DATE" and the value equal to the date "DD-MM-YY". The issue I am having is that the code I run adds the "DATE" and "DD-MM-YY values to the second column of a new row instead of appending to the existing rows in the data.

I've tried using both awk and sed, but both produce the same results. Below is my current code, my original data, the data resulting from my code, and my desired dataset.

Thanks in advance for your help!

for y in 2021 
        do
for m in  02
        do
for d in 01 
        do 
 awk -v d=$y-$m-$d -F"|" 'BEGIN {OFS = "|"} FNR==1{$(NF+1)="DATE"} FNR>1{$(NF+1)=d;} 1' Corporate_bond_mstr-$y-$m-$d.txt > check.txt  
done
done
done

and

sed  -e '1s/$/|DATE/' -e "2,\$s/$/|$y-$m-$d/" -e 's/\>|/ |/g' Corporate_bond_mstr-$y-$m-$d.txt > changed_$y-$m-$d.csv | column -s '|' -t  

ORIGINAL DATA

FINRA_SCRTY_ID|CUSIP_ID|SYM_CD|CMPNY_NM|SUB_PRDCT_TYPE_CD   
3698282|000336AC1|ANTM3698282|AAG HLDG INC|CORP|CORP   
3698282|000336AC1|ANTM3698282|AAG HLDG INC|CORP|BOND   
3698282|000336AC1|ANTM3698282|AAG HLDG INC|CORP|GOVT

DATA AFTER RUNNING CODE

FINRA_SCRTY_ID|CUSIP_ID|SYM_CD|CMPNY_NM|SUB_PRDCT_TYPE_CD   
       |DATE   
3698282|000336AC1|ANTM3698282|AAG HLDG INC|CORP|CORP   
       |DD-MM-YY   
3698282|000336AC1|ANTM3698282|AAG HLDG INC|CORP|BOND   
       |DD-MM-YY   
3698282|000336AC1|ANTM3698282|AAG HLDG INC|CORP|GOVT   
       |DD-MM-YY  

DESIRED DATA

FINRA_SCRTY_ID|CUSIP_ID|SYM_CD|CMPNY_NM|SUB_PRDCT_TYPE_CD|DATE   
3698282|000336AC1|ANTM3698282|AAG HLDG INC|CORP|CORP|DD-MM-YY   
3698282|000336AC1|ANTM3698282|AAG HLDG INC|CORP|BOND|DD-MM-YY   
3698282|000336AC1|ANTM3698282|AAG HLDG INC|CORP|GOVT|DD-MM-YY   

Answer 1

With GNU sed this will produce the desired data:

y=YY m=MM d=DD
sed -e '1s/[ ]*$/|DATE/' \
    -e '2,$s/[ ]*$/|'"$d-$m-$y"'/' data

Perhaps the column command is tricking you; try running without.