Postpone the memorial service — the expansion is still alive. For one month at least, business conditions improved for the banking sector, according to the latest reading of American Banker's Index of Banking Activity (IBA).

The IBA Composite Index climbed to 56.1 in September, up from a 53.2 reading in August and snapping a summer-long swoon that threatened to signal the first outright contraction since the index's inception in 2012.

Gains were broad-based but most prominent in indicators linked to commercial lending. Components that tracked both applications for and approvals of commercial loans surged in September. Respondents to the monthly survey in the Northeast and South regions of the US reported the strongest boosts in activity.

Noteworthy as well were modest improvements in the components that track pricing on new loans, which have been an area of persistent weakness for banks this year.

Given the relatively weak summer readings in the index, it remains unclear whether the rebound registered this month reflects a simple seasonal uptick or a true recovery in momentum. October's reading could help resolve that question.