If you scroll down at the bottom of the OCCRP (The Organized Crime and Corruption Reporting Project) site, one of the first sites to introduce the Panama papers to the public, you'll find that they are supported by OSF and USAID.
The Swiss leaks were mostly about the HSBC, even from the US side :
Later that year, in an account that so far has not been corroborated, Falciani said in an interview with the Spanish newspaper El País that he started working with U.S. Department of Justice officials on June 1, 2012. They warned him, he said, that the U.S. Senate “would be launching serious allegations against HSBC because of its lax money laundering and terrorist financing controls, and that the bank would be prosecuted. I was told that from then my life would be in danger. I had two choices: start a new life in the United States or travel elsewhere to buy some time.”
There were, indeed, hearings based on a report by the House Permanent Subcommittee on Investigations in July 2012, entitled “U.S. Vulnerabilities to Money Laundering, Drugs, and Terrorist Financing: HSBC Case History,” but according to a subcommittee aide, none of the data that Falciani had taken from the bank was provided to the committee or used in the investigation.
Subsequent to the Senate investigation, in July 2013, HSBC agreed to pay $1.9 billion to settle federal charges that it had enabled money laundering by Latin American drug cartels.
How can the US Treasury have its eye on anything going out in the age of multinational corporations that have their tax havens in Europe and pay negative taxes on their billion dollar profits ?
The Sorry State of Corporate Taxes
• One hundred and eleven of the 288 companies paid zero or less in federal income taxes in at least one year from 2008 to 2012. Fifty-five of these companies enjoyed multiple no-tax years, bringing the total number of no tax years to 203. In the years they paid no income tax, these 111 companies earned $227 billion in pretax U.S. profits. But instead of paying $79 billion in federal income taxes, as the 35 percent corporate tax rate seems to require, these companies generated so many excess tax breaks that they reported negative taxes (often receiving tax rebate checks from the U.S. Treasury), totaling $28 billion. These companies’ “negative tax rates” mean that they made more after taxes than before taxes in those no-tax years.1
• Twenty six of these corporations paid less than nothing in aggregate federal income taxes over the 2008-12 period. These companies, whose pretax U.S. profits totaled $170 billion over the five years, included: Pepco Holdings (–33.0% tax rate), General Electric (–11.1%), Priceline.com (–3.0%), Ryder System (–4.7%), Verizon (–1.8%) and Boeing (–1.0%).
How do these figures square with the well-known practice of corporations shifting their profits to countries like the Cayman Islands where they are not taxed at all? The figures here show what corporations report to their shareholders as U.S. profits and foreign profits, and therefore are likely to reflect profits genuinely earned in the U.S. and those genuinely earned offshore, respectively. But many of these corporations are likely to report something very different to the IRS by using various legal but arcane accounting maneuvers. Some of the profits correctly reported to shareholders as U.S. profits are likely to be reported to the IRS as profits earned in tax-haven countries like Bermuda or the Cayman Islands, where they are not taxed at all. Indeed, this partly explains the low effective U.S. income tax rates that many corporations enjoy. This “profit-shifting” problem will exist so long as our tax laws allow corporations to “defer” paying U.S. taxes on their “offshore” profits, providing an incentive to make U.S. profits appear to be earned in offshore tax havens.