The most common and most likely answer to this crossword clue is the 9 letter word FLOTATION
I've seen this crossword clue in Financial Times
F
L
O
T
A
T
I
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N
More clues leading to the result FLOTATION
Buddy explains!

The straight part
We know that "Financial activity" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case financial activity = flotation.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does FLOTATION mean?
FLOTATION noun- A state of floating, or being afloat.
- The ability (as of a tire or snowshoes) to stay on the surface of soft ground or snow.
- (chemical engineering) A process of separating minerals by agitating a mixture with water and detergents etc; selected substances being carried to the surface in air bubbles.
- The launching onto the market of a tranch of stocks or shares, usually a new issue.