The selected answer is incorrect.
According to Microsoft Support,
...bing.com and Bing Search API do not provide feature or query results parity...
The selected answer will return results from the News
API which contain or are relevant to the Query
top stories
. It will not return the same results as the Bing.com News (Top Stories) page.
In the new API, the Breaking News
query (an empty query parameter in Bing.com API v2) is not possible, as an empty query like https://api.datamarket.azure.com/Bing/Search/v1/Composite?Sources=%27news%27&Query=%27%27&Options=%27EnableHighlighting%27
will return a small set of old (for me, October 2014) items.
I have a ticket in to Microsoft Support about this, and will update once I hear more.