Perhaps the Fortune 500 Arizona-based business most vulnerable to a boycott is US Airways.  

Make no mistake, it's a racist law.  "A law whose real intention is to criminalise migrants, both legal and ‘illegal’, it is to make all brown people a suspect," observes human rights blogger Rick B.

Notwithstanding this observation, anti-immigrant sentiment alone may not be sufficient to account for the new law.  Arizona Senate Bill 1070 stands to benefit companies like Corrections Corporation of America (CCA). CCA
has partnered with the federal government to detain close to 1 million undocumented people in the past 5 years… Thanks to political connections and lobby spending, it dominates the industry of immigrant detention. CCA now has close to 10,000 new beds under development in anticipation of continued demand.
In an article describing "How politicians, the media, and corporations profit from immigration policies destined to fail," Tanya Golash-Boza writes: "Much of the success of CCA is due to its lobbying efforts and political connections, combined with the increased rates of detention for immigrants."    According to The Business of Detention one lobbyist for CCA was "Phillip J. Perry, son-in-law of Vice President Dick Cheney, who was appointed general counsel for DHS [Department of Homeland Security]."  In 2007, "CCA spent $3.25 million lobbying members of Congress to approve funding that would ultimately lead to increased spending on immigration detention."
CCA  is an important employer in some parts of Arizona:
As a partnership prison, CCA [Corrections Corporations of America] has been credited with helping Pinal County, Arizona, with being ranked No. 1 in a Money Magazine survey ranking the top 25 counties that have experienced the greatest job growth in the past eight years.
CCA facilities in Arizona contracting with the Bureau of Immigration and Customs Enforcement (ICE) include the Eloy and Florence correctional centers -- two of nearly one thousand immigration detention facilities nationwide (map).   The number of immigrants housed in ICE facilities have increased 300% since 1994.  The facilities are funded by federal tax dollars:  "Based on the amount budgeted for this fiscal year, U.S. taxpayers will pay about $141 a night — the equivalent of a decent hotel room — for each immigrant detained."  CCA boasts that its prisons bring economic benefits:  "communities in which CCA facilities are located realize many benefits, including new, career-driven employment opportunities, increased demand for local goods and services, and additional tax revenue."  Of course, a company like CCA is not creating new wealth. Rather, it is a mechanism for transferring taxpayer dollars from the many to the few. 

Is a boycott of Arizona justified?  It would appear as if the new law is at least as much a product of run-away corporatism as anti-immigrant fanaticism.  Given that Arizona politicians have positioned their friends to profit from a racist law at the expense of the whole country, it seems entirely fitting that Arizona-based companies should be made to pay for it.