The princes of Wall Street are losing their crowns and tightening their belts.

Massive layoffs and diminished bonus checks promise to put a crimp in the high-flying styles of stock brokers, money managers, investment bankers and once-untouchable hedge-fund geniuses. Bloomberg BusinessWeek described Wall Street as being in “retrenchment mode.” Thousands of layoffs either came or are coming and bonuses — the cash that turns brokers and bankers into big spenders — will reportedly be a fraction of last year’s.

Many who have kept their jobs have seen bonuses slashed nearly in half.

“Wall Street is the only industry where a seven-figure bonus is considered morally and financially insulting,” Robert Frank, wealth correspondent for CNBC and author of “Richistan,” told The Post. “I’ve heard from people getting $3 million bonuses and they are screaming at their bosses, threatening to leave — the cuts are meaningful to them. And the bosses are responding, ‘Leave to go where?’ All firms on Wall Street are dealing with the same bleak, financial landscape.”

They’re also already taking financial cover.

“Starting four months ago, every Wall Street guy I know tightened up. The St. Bart’s vacation got cut back by a day. The Aspen trip is done with one less girlfriend in tow,” a…