"All this will remain a mystery," he said.
Calling the settlement a significant conclusion after 12 years of litigation that resulted in scores of settlements and no trial involving airlines, the judge said, "Hopefully what was achieved was a measure of justice, a measure of reparation and closure."
He added, "But the lives that were lost were irreparable, and being irreparable, there now are no words to describe that loss."
The deal was announced by Cantor Fitzgerald attorney John Stoviak, who said money from various insurers is in escrow and ready to be paid out pending formal approval by the court at or after a Jan. 13 hearing.
Afterward, Cantor Fitzgerald CEO Howard W. Lutnick said in a statement that the case for insurance companies "was just another case, just another settlement, but not for us."
Lutnick, whose brother Gary Lutnick was killed in the attacks, added: "We could never, and will never, consider it ordinary. For us, there is no way to describe this compromise with inapt words like ordinary, fair or reasonable. All we can say is that the legal formality of this matter is over."
Cantor Fitzgerald lost 658 of 1,000 people in its New York workforce when the 101st through 105th floors of its One World Trade Center headquarters were destroyed when a hijacked airplane struck the tower. Howard Lutnick wasn't in the office.
Anthoula Katsimatides, who lost her brother John Katsimatides, a bonds broker, said she was "disheartened" to hear the case had been settled instead of going to trial.
"It would have been nice to hold people accountable" over issues including security, she said.
But she wasn't upset with Cantor Fitzgerald.
"I'm so confident that they are always thinking about the best interests of their Sept. 11 families ... there must have been a reason why they settled," she said.
Of this being the last airplane-focused case and therefore ending the chance to bring these issues up in open court, she said she was disappointed but, "I guess we just have to live with it."
A spokesman for American Airlines, which is based in Fort Worth, Texas, and is part of American Airlines Group Inc., said in a statement the airline had "vigorously defended itself in litigation brought against it by property owners and their insurers who allege that American should have done what the government could not do: prevent the terrorist attacks."
The spokesman, Sean Collins, also noted that "the courageous crew members and passengers on Flight 77 and Flight 11 were all victims of the terrorist attacks."
The judge praised lawyers on both sides, saying he once thought a deal was impossible. He noted that some litigation from Sept. 11, 2001, remains, including claims involving the trade center, developer Larry Silverstein, first responders and others.
Cantor Fitzgerald, meanwhile, has risen dramatically from a low of about 150 employees in the months after the attacks. It now has 3,200 employees in New York and about 8,000 worldwide, including the employees of a spinoff, BGC Partners.