Merging Several Csv Files in one Csv file

Question

Hi,
I have many csv file which do have same structure. I download those data from an external source like Yahoo bu it does not have headers. They jave just 6 columns of data Would you know how I can aggregate them in one file while including a column for each
set of imported csv file having its own file name, such as YHOO or WMT just next to the 6th column?
So, I have 2 questions: 
If ı can add them all in a file and if ı can add the seventh column (the name of each csv file to identify the stock in that combined file.)
Thank you so much for your support

Answer 1

Hi Everybody,
Thanks for the help. I have run the first code below:
$files  = "d:\temp\file1.csv","d:\temp\file2.csv"
$output = "d:\temp\output.csv"
foreach ($file in $files) {
 $contents = get-content $file
 foreach ($content in $contents) {
  $filename = split-path $file -leaf # get filename
  $a = $filename + ";" + $content | out-file $output -append
However, my goal  is to list companies in a tabular fashion (like file 1 should be listed in the first 6 columns of the file and second file is from 7-12 and third file 13-18 and so on).
So my goal is not to append all files below each other but next to each other.
Would you help me regarding that?
Kind Regards,