where can I find a list of the Market Participant Identifiers (MPID) and the actual company name?

Question

The MPIDs identify the market makers that process stock transactions.

Answer 1

The following table represents the definitions of the data fields contained in the download file. The download file contains all of the end-of-day registration statuses for all issues your MPID is registered in, for the date that was entered. The first four fields are the columns within the text file, and the last six fields are summaries located at the end of the file. This file is available as a self-extracting zip file.

Answer 2

NASDAQ Subscriber Services
Phone: [phone]
Fax: [phone]; ATTN: NASDAQ Subscriber Services Address: NASDAQ Subscriber Services; One Liberty Plaza, New York, NY