Municipal trade data

Municipal trade data is the transaction-level record of buying and selling in the US municipal bond market: every reported trade carries the security, price, yield, size and timestamp. MSRB's EMMA platform has collected trade reporting since 2005 onward and publishes it at four grains - 'per-trade, per-security, per-issuer and per-disclosure-document records' - with an estimated size in the millions of trade records. The same portal carries related munis material: official statements, continuing-disclosure filings and derived analytics such as yield curves, matching the tags 'trade data', 'munis' and 'yield curves'. Access is free through the web interface, which makes EMMA the reference implementation of this product category in investment-banking-brokerage data.

Transaction grain is what separates observable market activity from summaries of it, so the category sets a hard ceiling on what any muni analytics product can honestly claim. Two consequences follow for buyers. First, history: reporting runs from 2005 onward, so pre-2005 liquidity studies cannot be sourced here no matter what a vendor implies. Second, delivery: EMMA is free but its User Agreement prohibits crawling and systematic downloading, which blocks the bulk-harvest workflow most quant teams would otherwise run. A commercial feed that licenses redistribution solves the second problem at a price, and neither route changes the 2005 start date.

1. Verify the start date in writing. EMMA's coverage begins with 'trade reporting from 2005 onward'; any back-history claim needs a separate, named source.
2. Confirm the grain you are buying. EMMA supports per-trade, per-security, per-issuer and per-disclosure-document views; aggregated-only products cannot be re-disaggregated later.
3. Read the access terms before building a pipeline. The EMMA User Agreement prohibits crawling and systematic downloading, so scrape-based collection breaches the terms even though pages are public.

Entries that sit next to municipal trade data in this glossary:

• official-statements — Primary-offering disclosure documents for municipal bonds, hosted on EMMA as PDFs with document histories reaching back to the 1990s.
• web-scraping-access — Extracting structured records from HTML pages instead of calling an API, subject to each site's use terms.

Continuing disclosure - the post-issuance documents issuers file once securities are outstanding - is archived on the same EMMA platform and completes the trade-data picture.