With five deals in the market on Wednesday, the high-grade primary had already tallied US$76.9bn in new issuance even before all of the day's offerings had been launched.
Many syndicate desks were predicting only around US$70bn of total issuance this month.
But that was easily met in just a few sessions, helped by a US$19.75bn bond for Microsoft to help fund its purchase of LinkedIn - the fifth-largest corporate bond of all time.
Borrowers have also been pushing forward deals to avoid any volatility later in the year caused by uncertainty about the timing of a rates hike and the volatile US election.
The month's volume to date was enough to best the previous record August of US$71.565bn set in 2007, and well ahead of the US$49.775bn logged in August last year.
Here are the 10 biggest Augusts of issuance in the US investment-grade market. The 2016 total was set to increase later Wednesday once all the day's bonds have launched.