Like the old saying goes: What goes up must come down. And just as the fortunes of the world's wealthiest swelled during the post-crisis era as QE and ZIRP bolstered asset prices, now that trend has been thrown into reverse thanks to the turbulence in global markets during the second half of the year.

According to Bloomberg, even the world's richest individuals failed to find respite from a global market meltdown that has rendered 2018 the "worst year for markets on record."

Bloomberg's Billionaires Index showed that the 500 richest people in the world had a combined $4.7 trllion in wealth as of Friday's close, some $511 billion less than they had at the beginning of the year. With one week left to trade this year, 2018 is set to become the second year since the list was created in 2012 that the world's wealthiest have seen their wealth decline.

At their peak, soaring markets drove the aggregate wealth of the world's wealthiest above $5.6 trillion before the downturn began shortly after the Federal Reserve raised interest rates for the third time this year back in September.

"As of late, investor anxiety has run high," said Katie Nixon, chief investment officer at Northern Trust Wealth Management. "We do not expect a recession, but we are mindful of the downside risks to global growth."

Even Amazon founder and CEO Jeff Bezos, who saw his fortune swell to $168 billion earlier this year, has watched it fall more than $50 billion from the highs as FANG stocks have lead the market lower.

Even Jeff Bezos, who recorded the biggest gain for 2018, wasn’t spared the volatility. His fortune peaked at $168 billion in September, a $69 billion gain. It later tumbled $53 billion - more than the market value of Delta Air Lines Inc. or Ford Motor Co. - to leave him with $115 billion at year-end.

But Bezos' losses were mild compared with Mark Zuckerberg, whose net worth took the biggest hit among the world's tech titans.

The Amazon.com Inc. founder had a better year than Mark Zuckerberg, who recorded the biggest loss since January, dropping $23 billion as Facebook Inc. careened from crisis to crisis. Overall, the 173 U.S. billionaires on the list -- the largest cohort -- lost 5.9 percent from their fortunes to leave them with $1.9 trillion.

Billionaires in Asia lost a combined $144 billion...

Even Asia’s fabled wealth-creation machine stumbled as the region’s 128 billionaires lost a combined $144 billion in 2018. The three biggest losers in Asia all hailed from China, led by Wanda Group’s Wang Jianlin, whose fortune declined $11.1 billion. Despite the turmoil, Asia continued to mint new members of the three-comma club. The Bloomberg index uncovered 39 new members from the region in 2018, although that status proved short-lived for some. About 40 percent had lost their 10-figure status as of Dec. 7.

...While billionaires in Europe also saw their fortunes decline.

From Zara founder Amancio Ortega to former Italian Prime Minister Silvio Berlusconi, most of Europe’s billionaires saw their fortunes fall. Germany’s Schaeffler family, the majority shareholders of car-parts maker Continental AG, lost the most as extra costs and tough business conditions in Europe and Asia hampered the company’s performance. Georg Schaeffler and his mother Maria-Elisabeth Schaeffler-Thumann are $17 billion worse off than at the start of the year. That sum alone would place them among the world’s 100 richest people. Mexico’s Carlos Slim, the majority shareholder of Latin America’s largest mobile-phone operator, also suffered big losses. Once the world’s richest person, Slim now ranks sixth with a $54 billion pile. 3G Capital co-founder Jorge Paulo Lemann saw his fortune drop the most among Latin American billionaires, losing $9.8 billion. But even with that fall, he remains Brazil’s richest person. Russian fortunes on average fared better. The volatility caused by collapsing oil prices, a flare-up in tensions with Ukraine and tightening sanctions was partially offset by periodic gains. The combined net worth of the country’s 25 wealthiest people was down only slightly, ending at $255 billion, according to the ranking.

One outlier, though, was Russia, where billionaires fared better than elsewhere in the world (though only slightly).

Russian fortunes on average fared better. The volatility caused by collapsing oil prices, a flare-up in tensions with Ukraine and tightening sanctions was partially offset by periodic gains. The combined net worth of the country’s 25 wealthiest people was down only slightly, ending at $255 billion, according to the ranking. Still, 16 of the 25 Russian billionaires on the Bloomberg index saw their net worth fall in 2018. Aluminum magnate Oleg Deripaska, who remains under U.S. sanctions, lost the most -- $5.7 billion -- and dropped out the Bloomberg ranking of the world’s top 500 richest people. By contrast, energy moguls Leonid Mikhelson, Gennady Timchenko and Vagit Alekperov added a total of $9 billion. Timchenko, sanctioned in 2014, added 27 percent to his net worth as shares of gas producer Novatek rose 40 percent.

And if the co-CIO of the world's largest hedge fund is right, the aggregate net worth of the world's richest and most powerful individuas could be on track to worsen next year, which would, in our view, only ratchet up pressure on central banks to do whatever it takes to spare the global elite any more discomfort.