What would Trump's government shutdown look like? - ANZ

Analysts at ANZ explained that a US Government shutdown would be embarrassing, certainly, but not raising the debt ceiling by 30 September could result in a technical US bond default – and the two bills could yet be lumped together. 

Key Quotes:

"Fitch has commented that a government shutdown would not have a direct impact on the US’s prized AAA rating, but that failure to raise the debt ceiling “in a timely manner” very likely would.

Wall aside, Trump’s problem is that although the Republicans control both houses, fiscal hardliners in his party will want broad spending cuts attached to the bill, while moderates in insecure seats most certainly will not. US October T-bills have been pricing in an element of default risk since mid-July."