A Piece of Action.

A piece of the action
Meaning
A share in an activity, or in its profits.

Origin

'A piece of the action' has an unambiguously American flavour. It
brings to mind images of gangster movies with Jimmy Cagney and the
like demanding 'hey, gimme a pieca da action'. When the Star Trek
franchise opted for a mobster themed episode in 1968 they called it 'A
Piece of the Action'. It isn't essentially a US phrase though and
tracing its genesis takes us well outside the USA and into a history
of finance.

In the early 1600s, the Dutch came upon an interesting trading
innovation - the company. Until then, the spice trade had been
profitable but small scale, with spices being brought back from 'the
Indies' (broadly what we now call Asia) along the tortuous Spice Road
on pack horses. The high price of spices encouraged entrepreneurs to
build ships to bring the spices back in larger quantities. There was
big money to be made, but the large capital cost of building a fleet
and the threat of loss from pirates made it too risky a venture for an
individual investor; so, in 1602, they formed a company - the Dutch
East India Company.

Dutch citizens were invited to invest in the company, which had been
given exclusive trading rights to half the world and tax-free status
back home. Profits were huge and the clamour to invest was intense.
Dirck Bas Jacobsz, one of the company's founders, was instrumental in
managing the joint ownership by offering what were then called in
Dutch 'acties' or, in English, 'actions'. These were certificates that
promised a share in any future profits of the company and what, not
unnaturally, came later to be called share certificates. These shares
were often purchased by groups rather than individuals. What each of
these good citizens had bought was literally 'a piece of the action'.

The term 'action', which continued to be used in that context well
into the 19th century, was first recorded in English in John Evelyn's
Diary, published between 1641 and 1706:

"African Actions fell to £30, and the India to £80."

'A piece of the action' is certainly a 20th century American phrase.
Despite its 1930s mobster overtones, the first use of it that I can
find is in the 1957 film Monkey on My Back:

"You want a piece of my action, Sam?"

The 'action' in the phrase means 'a share in an activity; an
opportunity'. It is doubtful that whoever coined it in 1950s America
knew the history of the Dutch East Indies Company but, knowingly or
not, it was the Dutch 'acties' that were the source of that meaning of
'action'.