Guide · Python · SDK · REST API

MIC Validation in Python — ISO 10383 Exchange Codes

MIC codes identify exchanges and trading venues in trade reporting, order routing, and regulatory filings. Here's how the ISO 10383 standard works, the difference between operating and segment MICs, and how to validate them in your Python application.

In this guide

1. What is a MIC?
2. MIC structure
3. Why MIC validation matters
4. The right solution
5. Python code example
6. cURL example and response
7. Edge cases
8. Summary

1. What is a MIC?

A MIC (Market Identifier Code) is a standardised 4-character alphanumeric code defined by ISO 10383. It uniquely identifies exchanges, trading platforms, regulated markets, and other trading venues worldwide.

MIC codes are maintained by SWIFT on behalf of ISO and are updated regularly as new venues are created, existing ones are restructured, and terminated exchanges are retired. The standard is used across MiFID II reporting, EMIR trade repositories, FIX protocol messages, and virtually every institutional trading workflow.

ℹ️A single exchange can have multiple MIC codes. For example, NASDAQ has an operating MIC (XNAS) and several segment MICs for its different market tiers and trading systems.

2. MIC structure

Every MIC code is exactly 4 characters, all uppercase alphanumeric. The code itself is an opaque identifier — unlike ISINs or CFI codes, the characters do not encode structured meaning, though by convention many MICs start with X for exchange-level identifiers.

Property	Rule	Example
Length	Exactly 4 characters	XNAS
Character set	Uppercase A–Z and digits 0–9	XLON, XHKG
Type: Operating (OPRT)	Identifies the exchange or trading venue as a whole	XNAS (NASDAQ)
Type: Segment (SGMT)	Identifies a specific market segment within an operating MIC	XNGS (NASDAQ Global Select)

⚠️Operating and segment MICs are distinct codes. An operating MIC groups one or more segment MICs under it. When reporting trades, regulators may require either the operating MIC or the specific segment MIC depending on the jurisdiction and reporting regime.

3. Why MIC validation matters

MiFID II transaction reporting

Under MiFID II, investment firms must report the venue of execution using a valid MIC code. Invalid or terminated MICs cause trade reports to be rejected by national competent authorities, triggering compliance exceptions and potential fines.

EMIR derivatives reporting

EMIR requires counterparties to report derivative contracts to trade repositories with the execution venue identified by MIC. Using a decommissioned or incorrect MIC results in rejected submissions and regulatory scrutiny.

Order routing and smart order routing (SOR)

Trading systems use MIC codes to route orders to the correct venue. A mistyped MIC can route orders to the wrong exchange or cause routing failures, directly impacting execution quality and best-execution obligations.

Data quality and reference data management

Financial data feeds use MIC codes extensively. Validating MICs at ingestion time ensures that exchange identifiers in your database are current and correctly mapped to the right venues, preventing downstream data quality issues.

4. The right solution

The IsValid MIC API validates a MIC code against the official ISO 10383 registry and returns enriched venue metadata — including the exchange name, type (operating or segment), status, country, city, and website. The registry is kept up to date so you do not need to maintain your own copy of the SWIFT MIC database.

ISO 10383

Standard

official SWIFT MIC registry

<10ms

Response time

pure in-memory lookup

100/day

Free tier

no credit card

Full parameter reference and response schema: MIC Validation API docs →

5. Python code example

Using the isvalid-sdk package or the requests library. Install with pip install isvalid-sdk or pip install requests.

# mic_validator.py
import os
from isvalid_sdk import IsValidConfig, create_client

iv = create_client(IsValidConfig(api_key=os.environ["ISVALID_API_KEY"]))

result = iv.mic("XNAS")

print(result["valid"])        # True
print(result["found"])        # True
print(result["name"])         # 'NASDAQ'
print(result["type"])         # 'OPRT'
print(result["status"])       # 'ACTV'
print(result["countryCode"])  # 'US'
print(result["city"])         # 'NEW YORK'
print(result["operatingMic"]) # 'XNAS'

In a trade reporting pipeline — validating execution venue before submission:

# Validate execution venue MIC before regulatory submission
def validate_trade_venue(trade: dict) -> dict:
    mic = validate_mic(trade["execution_venue"])

    if not mic["valid"] or not mic["found"]:
        raise ValueError(f"Unknown execution venue: {trade['execution_venue']}")

    if mic["status"] != "ACTV":
        raise ValueError(
            f"Venue {mic['mic']} ({mic['name']}) has status {mic['status']} "
            f"— cannot report trades against a non-active venue"
        )

    # For MiFID II, some reports require the operating MIC
    return {
        **trade,
        "execution_venue_mic": mic["mic"],
        "operating_mic": mic["operatingMic"],
        "venue_name": mic["name"],
        "venue_country": mic["countryCode"],
        "venue_type": mic["type"],
    }

✅The API accepts both lowercase and uppercase input — it normalises the value internally. You do not need to call .upper() before sending the request.

6. cURL example and response

Validate an operating MIC (NASDAQ):

curl -H "Authorization: Bearer YOUR_API_KEY" \
  "https://api.isvalid.dev/v0/mic?value=XNAS"

Validate a segment MIC (NASDAQ Global Select):

curl -H "Authorization: Bearer YOUR_API_KEY" \
  "https://api.isvalid.dev/v0/mic?value=XNGS"

Valid MIC response (XNAS):

{
  "valid": true,
  "found": true,
  "mic": "XNAS",
  "operatingMic": "XNAS",
  "name": "NASDAQ",
  "type": "OPRT",
  "status": "ACTV",
  "countryCode": "US",
  "countryName": "United States of America",
  "city": "NEW YORK",
  "website": "https://www.nasdaq.com"
}

Invalid MIC response:

{
  "valid": false,
  "found": false,
  "mic": "ZZZZ"
}

Field	Type	Description
valid	boolean	Whether the input is a structurally valid 4-character MIC
found	boolean	Whether the MIC exists in the ISO 10383 registry
mic	string	Normalised (uppercase) 4-character code
operatingMic	string	The parent operating MIC (same as `mic` for OPRT types)
name	string	Official exchange or venue name
type	string	`OPRT` (operating) or `SGMT` (segment)
status	string	`ACTV`, `TERM`, `EXPI`, or `MODI`
countryCode	string	ISO 3166-1 alpha-2 country code
countryName	string \| null	Full country name, or `null` if unavailable
city	string	City where the venue is located
website	string \| null	Venue website URL, or `null` if unavailable

7. Edge cases

Operating vs segment MICs

An operating MIC (type OPRT) identifies the exchange as a whole. A segment MIC (type SGMT) identifies a specific market segment within that exchange. The operatingMic field always points back to the parent operating MIC.

# XNGS is a segment MIC under XNAS
segment = iv.mic("XNGS")
print(segment["type"])         # 'SGMT'
print(segment["operatingMic"]) # 'XNAS'
print(segment["name"])         # 'NASDAQ/NMS (GLOBAL SELECT MARKET)'

# XNAS is an operating MIC — operatingMic points to itself
operating = iv.mic("XNAS")
print(operating["type"])         # 'OPRT'
print(operating["operatingMic"]) # 'XNAS'

Terminated and expired exchanges

The ISO 10383 registry retains MICs for exchanges that have been terminated (TERM), expired (EXPI), or modified (MODI). These MICs are still found in the registry but should not be used for new trade reporting.

result = iv.mic("XVTX")
if result["found"] and result["status"] != "ACTV":
    print(
        f"MIC {result['mic']} exists but has status {result['status']} "
        f"— consider using the replacement venue"
    )

Status codes explained

Status	Meaning	Use in reporting
ACTV	Active — venue is operational	Safe to use
TERM	Terminated — venue has been decommissioned	Do not use for new reports
EXPI	Expired — MIC allocation has lapsed	Do not use for new reports
MODI	Modified — venue details have changed	Check updated details before use

8. Summary

❌Do not hardcode MIC lists — the ISO 10383 registry is updated regularly as venues change

❌Do not report trades against TERM or EXPI MICs — regulators will reject the submission

✅Check the status field — only ACTV MICs should be used for new trade reporting

✅Use operatingMic to resolve segment MICs back to their parent exchange

✅Validate MICs at data ingestion time to catch malformed venue identifiers early

✅Combine with ISIN and LEI validation for complete MiFID II and EMIR compliance

Validate MIC codes instantly

Free tier includes 100 API calls per day. No credit card required. Full ISO 10383 registry lookup with venue metadata, status, and operating MIC resolution.

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