A court in the southern Italian city of Trani cleared former S&P president Deven Sharma as well as four employees at the US agency after the prosecution had called for prison sentences of up to three years.
Fitch's head of operations David Michael Willmoth Riley, who risked nine months in prison, was also acquitted.
The two ratings agencies, whose probe the creditworthiness of borrowers, themselves came under the spotlight when they cut their ratings on Italy's sovereign debt, citing instability of the Berlusconi government of the day, and slow implementation of an austerity programme.
S&P lowered its rating by two notches in January 2012 to BBB+, having already cut it the previous September. The same month, Fitch also lowered its rating for Italy.
Trani prosecutor Michele Ruggiero argued that both agencies had violated European rating rules as well as rules of "fairness and transparency".
S&P, Ruggiero said, "deliberately provided financial markets with biased and inaccurate information concerning Italy's borrowing capacity".
The agency's decision to add a negative outlook to its notation as early as May 2011 went against official data given by the Italian government, he added.
He levelled similar charges at Fitch, adding that the agency's downgrade came during market opening hours when it was liable to provoke a substantial price reaction.
Several Italian consumer associations had come forward as plaintiffs.
S&P had rejected the charges as "completely unfounded".