Reuters / Lucas Jackson

Vanity Fair reported on Wednesday that before crucial points in the trade war, investors bought or sold thousands of electronically traded futures contracts, known as e-minis, on the S&P 500.

In one case, Vanity Fair said, a trader or group of traders made about $1.8 billion after buying 420,000 e-minis just before President Donald Trump said that talks with China were "back on track."

Those isolated trades have totaled about $3.5 billion, according to Vanity Fair.

"There is definite hanky-panky going on," a source described as a longtime Chicago Mercantile Exchange trader told Vanity Fair.

A Bloomberg article citing analysts poked holes in some of the Vanity Fair article's assertions.

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The trade war has consistently sent markets moving in the past year. And according to a new Vanity Fair report, some traders may have been forerunning new developments.

The magazine reported on Wednesday that some traders were suspiciously well positioned ahead of huge swings in the trade war by buying or selling hundreds of thousands of electronically traded futures contracts called "e-minis" on the S&P 500.

The magazine said that on September 10, a trader or group of traders bought 82,000 e-minis in the last 10 minutes of trading in New York, when it was almost 4 a.m. the next day in Beijing. A few hours later, the Chinese government announced it would lift tariffs on a range of American products. Markets surged, and the e-minis buyer made about $190 million, Vanity Fair found.

"There is definite hanky-panky going on, to the world's financial markets' detriment," a source described as a longtime Chicago Mercantile Exchange trader said. "This is abysmal."

Bloomberg was quick to rebut the assertions in the Vanity Fair article, saying that in some cases such sizeable bets would move the whole market and trigger trading halts, which never happened.

"Attributing sinister intent to a handful of trades that quickly became money-makers ignores how common such large trades are in the futures market," Bloomberg said, citing industry insiders.

Vanity Fair described a CME representative as saying that "the trades in question did not originate from a single source and they were of no concern."

Markets Insider has reported on the market impact of President Donald Trump's tweets — Morgan Stanley and Goldman Sachs have both analyzed how trade-related tweets have moved markets, with the former creating the "Volfefe index," a bot designed to analyze those movements.

Goldman's analysis found that traders believed that the president's tweets really did affect Federal Reserve policy, which, in turn, affects markets.

Read more: Ray Dalio warns the White House's latest plan to clamp down on Chinese investment could soon become a reality. Here's why he thinks 'all market participants need to worry.'

Vanity Fair said that on June 28, in the last 30 minutes of trading, someone bought 420,000 September e-minis — which stood out, as it was about 40% of the day's trading of those e-minis.

Shortly afterward, Trump emerged from a meeting with Chinese President Xi Jinping in Osaka, Japan, and said that trade-war talks were "back on track." The next week, the stock market surged, and whoever made that bet made a profit of about $1.8 billion, Vanity Fair calculated.

On August 23, markets were looking glum in the wake of poor trade-war news, and someone bought 386,000 September e-minis. The following week, Trump said that talks were going well in phone calls with China. (China said there were no calls.) Nevertheless, the S&P bounced 80 points, and the e-minis buyer made about $1.5 billion, Vanity Fair found.

"Every time stocks move after some crazy Donald Trump news — which, again, is every time stocks move — half the people who traded futures ahead of the move will look smart (and the other half will look dumb), and you can, if you want, build a conspiracy theory out of that," the Bloomberg opinion writer Matt Levine wrote in an analysis of the Vanity Fair article.

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