Stocks face two major tests this week-in the form of Nvidia earnings and a key Federal Reserve speech-that could potentially upend the market's surprising August rally.

Stocks have powered firmly higher since the end of July, with the S&P 500 rising nearly 5% over the past four weeks and printing a fresh all time high in mid August. Gains have stalled since then, however, amid a host of issues tied to the bond market, surging U.S. debt levels and a surprise move by Treasury Secretary Scott Bessent to hold down long term borrowing costs with beefed-up buybacks.

In fact, the benchmark is only around 2% higher than it was in mid-May, when it topped the 7500-point mark for the first time, thanks in part to underwhelming gains for the Magnificent Seven tech giants and the less-than-stellar summer performance of its North Star benchmark, Nvidia.

And that puts Wednesday's second-quarter earnings update, and more importantly its near-term industry outlook, firmly in the market's frame.

The AI chipmaker, and the market's biggest stock, is expected to post another set of impressive July quarter earnings after the close of trading, with a topline gain of more than 100% and a doubling of overall revenue to just over $92 billion.

"We're anticipating good news here, but so is everybody," says Mark Malek, chief investment officer at Siebert Financial. "Good news isn't good enough anymore, and any kind of misread or misstep could be a big challenge."

"What we're starting to see is that it's less about Nvidia itself and more about the broader implications, and the volatility across the market, since they're the root of the AI trade," he adds.

Markets will only have a day to digest the numbers, however, before a second, and likely more important, test on Friday, when Federal Reserve Chairman Kevin Warsh delivers his first keynote address to the central bank's gathering of the central banking elite at the Jackson Hole Economic Policy Symposium.

Richard Reyle, chief investment officer at Questar Capital Partners, sees a link between the two seemingly unrelated market signposts that was forged by Treasury Secretary Scott Bessent's intervention into the bond market last week.

"Nvidia needs to impress in order to keep one leg of the stock market stable," he says, citing the group's position at the epicenter of the AI buildout. "And Warsh needs to provide clarity on interest rates in order to stabilize the other."

The tech sector's sudden use of debt market financing to fund its AI ambitions, meanwhile, offers further connective tissue between Nvidia's second quarter update and Warsh's maiden Jackson Hole address.

"Through the lens of S&P options, this week's key catalysts span both the micro and macro fronts," say Barclays analysts, led by Stefano Pascale, in a note published Tuesday. "Notably, though, options are assigning remarkably similar risk to both events."

That combined view, however, raises the stakes heading into September, traditionally the weakest month of the year.

Jeffrey Buchbinder, chief equity strategist at LPL Financial, notes that once 10-year Treasury note yields start trading north of 4.3%, a threshold they crossed in late April, the correlation between yields and the S&P 500 generally turns negative.

But he still feels better about the earnings backdrop for stocks, the breadth of the market since late spring, and the power of the current AI investment cycle.

"While volatility tied to geopolitics, monetary policy, the midterm elections, or rising interest rates may come in the months ahead, a supportive fundamental backdrop raises the floor," he says. "At the same time, from a technical analysis perspective, the recent breakout by the S&P 500 to new highs raises the ceiling."

In the middle, however, sits the bond market, where 10-year yields sit uncomfortably close to their highest levels in 18 months, and traders are still pricing in a 40% chance of a Fed rate hike at next month's meeting in Washington.

Overall U.S. debt topped $40 trillion last week, this year's deficit is likely to rise past $2 trillion, and Bessent's interventions have rattled investor confidence.

Global oil prices, meanwhile, are likely to stoke inflation prospects, while President Donald Trump's latest trade salvos against Canada, alongside his economic sanctions against Iran and its trading partners, will add further uncertainty over the coming weeks.

Navigating that thicket of risks, while maintaining a vow not to guide markets on the central bank's near-term rate path, will pose a significant challenge for Warsh when he takes the podium on Friday.

Jonathan Pryor, head of private markets & co-head of dealing at Marex FX, thinks Warsh's Jackson Hole address will be about "establishing what kind of Fed chair he wants to be."

"Markets will be looking not just for clues on the next rate move, but for a clearer sense of how he'll lead the Fed through this environment," he says. "If he can establish that, Jackson Hole could prove more important for his credibility than for the immediate direction of rates."

Markets might need assurance on both, alongside a bullish tenor from Nvidia, heading into a suddenly uncertain autumn.