Modified broad match (BMM) was a Google Ads keyword match type, now retired, that let your ad show only when every word marked with a plus sign appeared in the search, in any order. A keyword written as +emergency +plumber would match “plumber needed for emergency in Leeds” but not “emergency electrician”.
How modified broad match worked
Each word you wanted to lock in got a plus sign in front of it. The search had to contain that word or a close variant of it, such as a plural or a misspelling, but extra words could appear before, after or between them, and the order did not matter. It sat between broad match, which could match searches without any of your words, and phrase match, which used to require the words in a fixed order.
For years many advertisers built whole accounts on it, because it caught the long, varied searches people actually type while keeping out the wildly unrelated matches broad match produced at the time.
What happened to it
In 2021 Google merged modified broad match into phrase match. Phrase match was widened to pick up most of the searches BMM used to catch, while still respecting word order where it changes the meaning; “London to Paris flights” and “Paris to London flights” are treated differently. From mid-2021 you could no longer create new BMM keywords. Existing ones were not deleted: they carried on serving, but under the new phrase match behaviour. Microsoft Advertising made a similar change soon afterwards.
So today there are three match types: broad, phrase and exact, explained together under keyword match types. Any keyword you still see with plus signs is a leftover that behaves as phrase match.
Why it matters
It matters mainly when you inherit or audit an older account. A UK account built before 2021 may still hold hundreds of plus-sign keywords alongside phrase match versions of the same terms. They now compete with each other for the same searches, split data and make reports confusing.
It also matters when you read advice. Plenty of guides still recommend BMM as a safe middle ground, and some agency proposals still describe it. Advice written around a match type that no longer exists is a sign the rest of the guidance may be out of date too.
Common mistakes
- Believing plus-sign keywords still behave as they did before 2021.
- Keeping BMM and phrase match versions of the same keyword in one ad group, splitting the data.
- Typing plus signs into new keywords out of habit, for a match type that no longer exists.
- Following old guides that build entire campaigns around BMM.
- Assuming broad match today works like broad match before 2021. It now relies heavily on Smart Bidding and signals, and behaves quite differently.
How to act on it
If your account predates 2021, filter the keyword list for a “+” and review what you find. Where a BMM keyword has a phrase match twin, keep the one with the better history and pause the other. Where it stands alone, recreate it as phrase match so it is clearly labelled, then check the search terms report over the following weeks. Tidying old match types is a routine first step when I take over an account to run Google search campaigns.