The investigations by the United States attorney's offices in Philadelphia, Boston and San Francisco have been disclosed before.
Shareholders said Merrill's mounting losses and bonus plans should have been disclosed before investors voted on the merger in December 2008.
While several of those alleged plots had been disclosed before, officials said that the 2002 effort had not been publicized until now.
The documents have been disclosed before a trial due later this summer at the investigatory powers tribunal, which hears complaints about state-authorised surveillance and the intelligence agencies.
In a statement, the editor in chief of Guardian US, Janine Gibson, said, "Under our guidelines, the relationship between Joshua and the agency should have been disclosed before the piece was published in order to give full clarity to our readers".
Many of the details had been disclosed before by officials briefed on interviews with the crew during and after their 11 days that the Americans were held in China.
"Under our guidelines, the relationship between Joshua and the agency should have been disclosed before the piece was published in order to give full clarity to our readers," said Janine Gibson, editor-in-chief, Guardian US. "I vigorously affirm that nothing unethical was done and I have been open with the Guardian in this matter.
The outlines of the surveillance programs had been disclosed before, but NSA leaker Edward Snowden revealed their stunning sweep when he released reams of material earlier this year.
It is the case of the already cited WannaCry attack, which has the EternalBlue exploit, which has been disclosed two months before the attack, as one of its elements.
