The pair had been accused on nine counts that alleged they had deliberately misled investors about the financial state of two hedge funds they ran.
But the jury took less than nine hours to return a not guilty verdict on all of the charges that had been made against them.
After the case, jurors told the media that the government's prosecution, which had been based on excerpts from emails between Tannin and Cioffi, had not given them enough evidence to go on.
Speaking to Bloomberg, one said that the men had been made "scapegoats for Wall Street".
Bear Stearns, which is now a subsidiary of JPMorgan Chase, recently reported net income of $3.6 billion for the third quarter of 2009, as it begins to recover from the financial crisis that first engulfed Tannin and Cioffi's hedge funds before resulting in the collapse of the company itself.
By Tony Aynsley