Mario Buda (1883–1963) was an Italian anarchist who was active among the militant American Galleanists in the late 1910s and best known for being the likely perpetrator of the 1920 Wall Street bombing, which killed 40 people and injured hundreds.

After working itinerant jobs across the United States and a short return to Romagna, Buda settled in Boston's Roxbury neighborhood, where he ran a cleaning company and grew close to Italian anarchists and disciples of Luigi Galleani.

Buda's car was the link in the Boston robbery investigation that led to the arrest of Sacco and Vanzetti, a landmark American trial.

During the 1930s, however, he became a collaborator of the Italian Fascist secret police OVRA and was involved in foiling an anarchist plot against Benito Mussolini, for which Buda's name was scrubbed from the state list of radical subversives.

In search of higher wages, Buda went west to Colorado but could only find work upon returning east to Washington, Illinois, and Wisconsin.

[4] He settled in Boston's Roxbury neighborhood, a home to Romagna Italians like himself and Galleanists, acolytes of anarchist Luigi Galleani.

[8] As they slowly dispersed back to the United States,[7] additional news of Galleani's arrest and Italian anarchists killed in Milwaukee drove them to retaliate.

[10] In September 1917, a pastor held a patriotism rally near a local Galleanist meeting spot in Milwaukee's Bay View neighborhood.

Incensed by this Bay View incident, Buda traveled to Chicago, the center of Midwest Italian anarchism, where he made plans to retaliate[11] and worked for several months.

[12] In November 1917, a retaliatory bomb was left in the Milwaukee pastor's church and transported for inspection to the city's police station, where it exploded, killing 10.

Though the bombmaker was never identified, historian of anarchism Paul Avrich wrote that Buda was most likely responsible for the attack with assistance from his comrade Carlo Valdinoci, who had been living in Youngstown.

[13] Operating under the pseudonym "Mario Rusca", Buda was likely also involved in the Youngstown plot to supply Ella Antolini with a suitcase of dynamite in January 1918 to deliver from Ohio to Milwaukee for use in further attacks.

[16] He retreated to Iron River, Michigan, where he worked under the assumed name "Mike Boda"[17] both on the railroad and in selling bootleg whiskey.

[26] The police met Buda in late April 1920 when investigating Ferruccio Coacci, an Italian anarchist who had been eager to hasten his deportation.

After hearing that Buda's car was in a local garage for repair, the Bridgewater police chief suspected that it had been used in the South Braintree crime.

[27] By early May, escalating fears from the federal investigation of Italian anarchists in New York City and the possibility of raids from the Department of Justice led the Boston Galleanists to need Buda's car[29] to dispense of propaganda or explosives that would lead to their deportation.

Fearing deportation and knowing neither their rights nor the crime of which they were being accused, Sacco and Vanzetti proceeded to lie about their politics and knowledge of Buda, leading the prosecution to build a case around the suspects' apparent "conscience of guilt".

[32] Buda was incensed at the persecution of his close friends between the maximum, 12-to-15-year sentences levied on Sacco and Vanzetti for the Bridgewater robbery (in which there had been no injuries or goods stolen) and new September indictments against them for the South Braintree murders.

[33] Buda prepared his next retaliatory steps in Boston and traveled to New York, where he loaded a horse-drawn wagon with a timed dynamite bomb filled with cast iron slugs.

After a wide sweep of the eastern seaboard in which hundreds were questioned and a $100,000 reward offered, the investigation ended unsuccessfully with the bomber unidentified.

[38][39] Some time after the Wall Street bombing, Buda returned to Providence, Rhode Island, where he acquired a passport from the Italian consulate.

The police believed he manipulated evidence, and in November 1927, Buda was sent to serve five years on Lipari, an island colony for political prisoners off the coast of Sicily.

Between 1937 and 1939, Buda helped foil a plot against Italian dictator Benito Mussolini by the Trieste anarchist Umberto Tommasini, whom he likely met in Ponza.

Historian Paul Avrich wrote that Buda was known to be calm, with a thoughtful manner and stubborn pride and,[2] like the other Galleanisti in Mexico from Italian peasantry, intensely tenacious, loyal, with a tough conviction.