# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/(.*)\r?\n(.*)\r?\n(.*)(?:\r?\n|$)/$1|$2|$3\n/gm;t' <<< "1000
AAAAAAAAAA
100,000.00
2000
BBBBBBBBBB
200,000.00
3000
CCCCCCCCCC
300,000.00
4000
DDDDDDDDDD
400,000.00"
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for SED, please visit: https://www.gnu.org/software/sed/manual/html_node/The-_0022s_0022-Command.html