Earlier this month, I described the size (and, by extension, the index influence) of Nvidia’s daily market-cap swings as “farce.”

It was an apt description. By now, a history of the largest single-session value creation bonanzas and biggest one-day wipeouts is just the record of Nvidia ca. 2023/2024.

At various intervals since May of 2023 — when the company changed the world with what it’s probably fair to call the most famous beat and raise in history — market observers have joked that the S&P 500 is really just the “S&P One.” Personally, I don’t think that joke’s very funny. Because on some days, it’s true, and that’s terrifying.

Take September 11, 2024, for example. Mid-week, the S&P and the Nasdaq 100 swooned in the wake of a warmer-than-expected read on core consumer price growth in the US, but by session’s end, both benchmarks had successfully pared large intraday declines to close sharply higher. The turnaround catalyst was Nvidia and, naturally, flows.

The figure below shows you the mid-week market cap gain for Jensen Huang’s miracle machine.

Nothing to see here everybody, just another $216 billion single-session swing.

The rally was courtesy of Huang himself who, while regaling a packed house at a Goldman tech conference, said demand for his products is “so great” that customers are getting “emotional,” creating “tense” relationships between the company and its buyers. “We’re trying to do the best we can,” he said.

That’s obviously ridiculous — not in the sense that Huang’s exaggerating, but precisely because he probably isn’t — but it helped rekindle investors’ AI joie de vivre, which waned following Nvidia’s earnings release late last month.

Huang’s remarks served as “confirmation” of Larry Ellison’s unbridled bullishness from earlier this week. Ellison — whose net worth rose by $14 billion in a single day following Oracle’s results, vaulting him over Bill Gates on Bloomberg’s demigods list — described “an ongoing battle for techn[ological] supremacy that will be fought by a handful of companies and maybe one nation state over the next five years at least, but probably more like 10.” “There’s no slowdown or shift coming,” he told investors.

As one Nomura PM cited on Thursday by the bank’s Charlie McElligott noted, this isn’t just suppliers talking their books. At the same Goldman event, both Microsoft and Amazon soundly equally excited (assuming that’s possible when the excited bar’s set by Huang) which, as Charlie put it, suggests there’s currently “no limit on what they’re willing to spend due to the importance of [the AI] theme across their businesses.”

And so, Nvidia rallied hard, pulling the entire market along for the raucous ride. McElligott called it an “NVDA–induced equities FOMO euphoria.” “The world’s largest wealth creation machine went into overdrive and fed into a virtuous feedback loop across the reality of today’s market structure,” he wrote.

The figures show you the share of September 11’s rally attributable to Nvidia. The stock single-handedly accounted for 44% of the S&P’s mid-week gain.

Just as important, in my view anyway, as Nvidia’s mathematical contribution to the index gain was the read-through of the shares’ march higher for flows.

“The outsized moved in the single-name set off a cacophony of accelerant flows with both real and synthetic negative gamma creating more buying of shares the higher the underlying stock travelled via options market maker-hedging” on calls they’re short to clients, in addition to “the prolific importance which NVDA has across the largest components of the leveraged ETF space,” Charlie wrote.

The figures below, with helpful annotations from McElligott, give you a sense of these dynamics.

Nvidia apparently accounted for nearly $1 of every $4 of options traded on September 11.

So, that’s it. That’s what makes a rally these days: Nvidia plus modern market structure gets you sessions like Wednesday’s.

McElligott summed it up as only he can. “When a name of this magnitude sees an outsized move, there will be a large mechanical impact from its index weighting knocking across the entire ecosystem,” he wrote, describing September 11’s trade as the “latest expression of Nvidia’s central bank-like power.”