sql - concat two strings totalling >4000 characters

Question

I am trying to combine two columns from one table (A) into on column in a second table (B). The column in table B is set as CLOB to hold the large amount of data, however when I run the script I get a message that the result of my string concatenation is too long.

INSERT INTO berkshire.tim_rebuttal_prod(
,INVEST_OR_UWG
)
SELECT 
,(INVEST_OR_UWG || INVEST_OR_UWG2)
FROM berkshire.stage_rebuttal

Answer 1

select rtrim(xmlagg(xmlelement(e,id,',').extract('//text()') order by id).GetClobVal(),',') from (select level as id from dual connect by level < 1050)