Tim Cook answered
The letters S.p.A, as in Fiat S.p.A, stand for Società per Azioni. Fiat itself is also an acronym: Fabbrica Italiana Automobili Torino.
The company is owned by shareholders and in Fiat's instance, their shareholders voted for Fiat to be merged into a new Dutch concern as from October 2014, to be called Fiat Chrysler Automobiles NV.
Other Possible Meanings for S.P.A
The acronym has other uses in the world of business, including Systems Planning and Analysis, which supports American national security programs, and are based in Alexandria, Virginia, USA. SPA could also mean Sony Pictures Animation, the company responsible for films such as Open Season and The Smurfs.
For more on the history of Fiat, watch this fim: