Jeffrey David Olson's attorney argued in court that his client was engaging in a legal protest with no malicious intent.
"His purpose was not malicious. His purpose was to inform," Tom Tosdal told the jury.
Olson was charged with vandalism for writing messages including "No thanks, big banks" and "Shame on Bank of America" in chalk on the sidewalk in front of three branches.
After the verdict was read he told reporters he was shocked that he was charged with vandalism in the first place.
"I never thought in a million years that using washable sidewalk chalk on a city sidewalk could be considered vandalism. That was unfathomable to me," he said.
The prosecution argued that Olson's messages were "graffiti" and that they caught authorities's attention because "he went back again and again and again."
The San Diego City Attorney's office release a statement explaining that they respected the jury's decision and adding that they receive "about 20,000 criminal cases annually, referred to us by the San Diego Police Department."
"This case was referred to our office by SDPD and was issued by prosecutors in the Neighborhood Prosecution Unit. That unit is charged with, among other things, working closely with SDPD's Graffiti Strike Force. Our prosecutors never treated this case as anything more than a graffiti case. As with most graffiti cases, Mr. Olson was offered reduction to an infraction after completing volunteer work service cleaning up graffiti. His refusal of that offer resulted in the trial and his successful defense."