Broad match negative keywords behave much like the bidded broad match keywords. However, the intent here changes. Broad match negative keywords aim towards restricting as many search queries as possible.
Here is all that you need to know about AdWords Negative Keywords and their match types.
Before adding a term as negative keyword and assigning the broad match type to it, here are a few things to keep in mind:
1. It restricts your ad from showing for search queries if all the words are present in the query irrespective of the order. For e.g., if you have red socks as a negative keyword then your ad will not be triggered for search terms such as red ironed socks, buy red socks. So, it is advisable to be doubly sure of a keyword before adding it as a broad match type negative keyword.
2. Unlike broad match keywords, negative broad match type do not include close variants or synonyms. So, for any variation of your broad match negative keyword, your ad will still be triggered. In such a case, you must add the close variant also as negative keyword separately.
3. If your negative keyword constitutes of a single word, then assigning broad or phrase match will not make any difference to it. So, a negative keyword such as free added as a phrase or broad match will still end up blocking your ad from showing for search terms such as free red socks, buy one get one free etc.
4. In some cases it might make more sense to use phrase match instead of broad match, especially when the order of the keyword carries relevance. For instance, keyword Wellington Hotel and Hotels in Wellington both would serve different intent. Where the former would be searches related to the brand ‘Wellington Hotel’, the latter is search related with hotels in Wellington (New York).
5. There is no modified broad match negative keyword as broad match negative keywords work similar to how the modifier broad match would work.
6. By default a negative keyword is assigned the broad match type. So, if you wish to assign any other match type to the negative keyword, make sure to assign the appropriate match type.
For the entire post on using broad match negative keywords effectively click here.