New issues are, functionally, credit expansion, and support GDP to the extent the funds are spent on real goods and services.
But note that the US housing agencies are turning over their profits of about the same $5 billion/mo to the Treasury, which works against GDP, to the extent those funds would have otherwise have been spent on real goods and services.
At the macro level it’s a continual give and take between deficit spending and the demand leakages.
New US listings at post-crisis high in Q3
August 8 (FT) — The market for new US listings is off to its best third-quarter start since before the financial crisis. A total of 28 companies have raised $5.2bn from US initial public offerings since July, which marks the fastest rate of activity and amount raised in the same period since 2007, according to data from Dealogic.