Standard & Poor’s, the giant credit rating agency accused of inflating the subprime mortgage bubble, had long been convinced that a Justice Department lawsuit lacked merit. So convinced, in fact, that it portrayed the lawsuit as an act of “retaliation” for its decision to cut the credit rating of the United States in the summer of 2011.

Now that S.&P. is poised to settle that case, as well as lawsuits from 19 state attorneys general across the country, the rating agency is walking back that claim.

As part of a $1.37 billion settlement deal expected this week, S.&P. has agreed to acknowledge that it never found evidence supporting its accusations of retaliation, people briefed on the matter said.

The Justice Department, which long scoffed at S.&P.’s claims, had emphasized the retraction as a sticking point in the settlement talks. S.&P. eventually agreed, the people said, though its acknowledgment does not address whether additional depositions would have yielded a different conclusion.

The concession — an unexpected about-face for the rating agency — will appear as one element in a broader statement of facts that S.&P. negotiated with state and federal authorities. While S.&P. agreed to many of the government’s demands, the people said, it managed to avoid an admission that it had committed fraud, an important victory for the rating agency.

As the S.&P. case winds down in the coming days, closing the book on one of the government’s signature Wall Street cases, other investigations stemming from the financial crisis are gaining steam.

S.&P. was not the only rating agency to draw scrutiny. After more than four years of investigating the role of Moody’s, S.&P.’s rival, in stoking the mortgage crisis, the Justice Department recently secured a breakthrough, the people briefed on the matter said. It is too soon to tell, however, whether the recent developments will breathe enough new life into the long-running inquiry that Moody’s will face a lawsuit. The Connecticut attorney general’s office, which was one of the first to sue S.&P., also filed a case against Moody’s.

Some banks also remain on the government’s radar. The Justice Department, which already obtained tens of billions of dollars from banks suspected of duping investors into buying troubled mortgage investments, has turned its focus to Morgan Stanley, one of the people briefed on the matter said. A settlement is expected in the first quarter of the year.

The investigations into Wall Street misdeeds typically follow a similar path: one that results in a settlement. It is rare for a financial institution to gamble its fate in the courtroom, fearing that a protracted legal battle would alienate the government and unnerve shareholders.

S.&P. bucked that trend. Faced with demands that it pay more than $1 billion to settle with the Justice Department and the state attorneys general — similar to the demands that it has now accepted — it initially chose to fight instead.

The Justice Department’s lawsuit, filed two years ago this week, accused S.&P. of fraud. Saying that S.&P. falsely claimed that its ratings “were objective, independent, uninfluenced by any conflicts of interest,” the lawsuit argued that S.&P. actually inflated its ratings of mortgage securities to appease the Wall Street banks that had devised the investments. A conflict of interest — the banks paid S.&P. to rate the deals — “improperly influenced” the ratings criteria, the Justice Department said.

S.&P., a unit of McGraw Hill Financial, fought back, saying that its claims of objectivity were mere “puffery,” akin to corporate marketing, and could not be taken seriously. The rating agency, which called the Justice Department’s lawsuit “meritless” and vowed to fight it “vigorously,” hired at least five law firms to handle the case.

The lawyers engineered a broad response to the government. Indeed, in its answer to the Justice Department’s complaint, S.&P. offered 19 different defenses to the charges. But one defense — that the Justice Department “commenced this action in retaliation” for the downgrade of the United States credit rating — garnered the most public attention.

“Only S&P Ratings downgraded the United States and only S&P Ratings has been sued by the United States,” the filing noted.

S.&P. then took its claims a step further, submitting an affidavit from an S.&P. executive who said that Timothy F. Geithner, the Treasury secretary at the time of the downgrade, had warned that S.&P.’s conduct would be “looked at very carefully.”

At the time, a spokeswoman for Mr. Geithner said that “the allegation that former Secretary Geithner threatened or took any action to prompt retaliatory government action against S.&P. is false.”

But that did not stop S.&P. from subpoenaing Mr. Geithner. The judge overseeing the case supported the S.&P.’s request.

Floyd Abrams, a noted First Amendment lawyer who often represents S.&P., ultimately became the face of the retaliation defense.

During an appearance on CNBC on the heels of the Justice Department’s filing of the case, Mr. Abrams was the first to link the federal investigation to S.&P.’s decision in 2011 to cut the United States credit rating below the top grade of AAA.

“The intensity of the investigation,” he told the network, “significantly increased” after the downgrade.