A stock market expert who called the 2008 crash says a similar market crash, like the one in December of 2018 is inevitable. Former Goldman Sachs alumnus Raoul Pal said in an interview with Market Watch: “We’re coming into a period of illiquidity for equities.”

Pal is the author of the Global Macro Investor newsletter which is followed by the world’s biggest hedge funds. He cites three reasons why a repeat of the stock selloff of December 2018 may be inevitable. The first is the blackout period for companies, which hits around earnings time when their share buybacks start to slow. Secondly, he notes that this year has also seen problems with the short-term borrowing market, or repo market, that the Federal Reserve has been trying to tackle. It could mean less buying from market makers — who help create liquidity for markets by bringing buyers and sellers together, according to a report by Market Watch. 

But the biggest problem facing the stock market in December, according to Pal, is baby boomers.  That’s right. Americans born between the mid-1940s and mid-1960s are doing damage to the economy if Pal is to be believed. They face an annual requirement to sell about 5% of their individual retirement accounts, loaded with stocks in some cases, as they reach 70.5 years old.

“The problem is the gap between this year and last year is huge. It’s like [a] 50% increase in the amount of selling that has to be done,” said Pal. “They have to start selling by year-end. If you take out the Christmas week and you’re a financial adviser, and you want to get this done early, you will start in October.”

[Pal] blames boomer selling for part of the meltdown for stocks late last year. “The marginal change of an American baby boomer thinking ‘I’ve got too much equities,’ which they do have — that is catastrophic for the system, because they have way, way too much risk,” says Pal, co-founder of Real Vision financial television. -Market Watch

Pal called the 2008 market crash and he said a repeat of last year’s December selloff is inevitable.  Take his opinion with a grain of salt if you’d like.