With Donald J. Trump on the clock to secure a nearly half-billion-dollar bond in his civil fraud case, a New York appeals court appears to have handed the former president a lifeline on Monday, accepting a far smaller bond of $175 million.

The ruling by a five-judge panel of appellate court judges was a crucial and unexpected victory for the former president, potentially staving off a looming financial disaster. Had the court denied his request — and had he failed to obtain the full bond — Mr. Trump risked of losing control over his bank accounts and, eventually, even some of his marquee properties.

For now, those dire outcomes might be on hold. If Mr. Trump obtains the smaller bond, it would prevent the New York attorney general’s office, which brought the fraud case against him, from collecting the $454 million judgment imposed by a trial judge while Mr. Trump appeals. The appeal could take months or longer to resolve.

Mr. Trump has 10 days to secure the bond, and two people with knowledge of his finances said he should be able to do so by then.

A spokeswoman for the attorney general, Letitia James, did not immediately respond to a request for comment.

An appeal bond is a promise from an outside company that it will cover his judgment if he ultimately cannot pay. In order to obtain one, Mr. Trump must pay the bond company a fee and pledge a sizable sum of cash as collateral. Mr. Trump need not turn over the collateral for now, but the bond company would be entitled to collect it if he failed to pay.