Accused sex-fiend financier Howard Rubin blew a kiss to his wife after being ordered kept behind bars Monday.

Rubin was ordered held by a Brooklyn judge who said even a $50 million bond package isn’t enough to guarantee the suspect won’t flee.

The ​70-year-old retired Wall Street powerhouse, who was charged with sex-trafficking along with his personal assistant Jennifer Powers, is being supported by his chummy estranged spouse, Mary Henry, who already wrote the court a letter begging for his release.

The former couple ​is going through divorce proceedings, but Henry still described Rubin as a loving family man.

​But federal prosecutors successfully argued Rubin remains a danger to the community and could flee from authorities if let out.

“Fifty million dollars seems like a lot of money to a layperson, but it may not be a lot for this defendant and his family,” Magistrate Judge Brian James Cho said during ​the hearing in Brooklyn federal court.

Rubin​, wearing a jail-issued tan jumpsuit and black glasses, let out a chuckle when another judge asked him at an earlier status hearing Monday how he was doing during his detention, which started in late September when he was arrested.

“OK,” ​the deep-pocketed suspect responded with a wry half smile.

Rubin’s lawyer, Michael Gilbert, tried to stress to Cho that his client is getting up in age and the fact that he suffered a stroke in July.

“This conduct is old,” Gilbert said of the allegations.

The lawyer also previewed his trial defense, saying the accusations stem from “private sexual activity involving adults.”

But the judge ordered Rubin to remain behind bars till trial. Prosecutors say they still don’t know exactly how wealthy Rubin is. He has a​t least a $74.4 million account in the Cayman Islands, they said.

Rubin waved to Henry on his way into the courtroom —  then blew her and their daughter a kiss as he was taken out.

Both Henry and his daughter Annalee Rubin went to bat for the suspect leading up to the hearing.

“I understand far too well the serious charges before the court,” Henry wrote in a letter to the judge. “I can only speak from my own experience when I say they do not represent the Howie Rubin I saw: a caring father, a loving son-in-law, and devoted grandfather known affectionately as ‘Pops.’​ ”

Annalee described her father as someone who goes “above and beyond to create joy for his grandchildren.

“He dresses up in costumes—like characters from Frozen—just to make them smile,” she wrote.

“He even turned the living room in his home into a tumbling mat and ball pit play area so the kids would have a special gym-like space to enjoy.”

Federal prosecutors dismissed ​their arguments in a court filing, insisting Rubin at times flouted family obligations to pursue BDSM sex with women and his family ties didn’t stop his alleged sex-trafficking. 

“It is unremarkable that he may have treated his family and friends with kindness, as most people do,” prosecutors wrote in an Oct. 19 memo.

“That does not change the troubling fact that for at least a decade, the defendant brutalized women, often while they were gagged and restrained in his locked Dungeon, helpless to make the violence stop.”

Rubin​ and Powers, 45, are accused of luring scores of women to the Big Apple, where Rubin allegedly tormented them inside his penthouse-turned-BDSM dungeon.

The scheme, which also involved ritzy hotels, lasted for about a decade.

The two were ​previously sued over similar allegations, though only Rubin was found liable.

Rubin is also facing a bank fraud charge while Powers and her husband Steve are facing federal​ raps for alleged tax fraud.

The wealthy money manager who once worked for George Soros’ fund allegedly funneled millions of dollars to the Powers over several years that the couple didn’t report to the IRS.