A 5.32% Long Bond Beats Foreign Buying: KOSPI Loses 7,000 as Nvidia Backstops $105B

The KOSPI opened 2.15% higher at 7,127.77, ran to 7,216.62, then closed at 6,869.83, down 1.55% [s1c1][s1c2]. The cause was imported: the U.S. 30-year Treasury yield surged to 5.32%, its highest since 2007, while Brent crude rose to $90.87 amid the worsening war involving Iran [s1c3][s1c4][s1c5].

That is a peak-to-close reversal of 346.79 points, or 4.81% ^[1]. The intraday swing of 427.84 points was the widest so far in August, which puts the session low near 6,788.78 [s1c6]^[2]. It happened with the bid in place: foreign investors extended net buying on the main bourse for a fifth straight session from the 11th, running 2 trillion to 3 trillion won a day from the 12th to the 14th, and the won-dollar rate fell to 1,411.8 [s1c7][s1c8][s1c9]. When flows are that strong and the index still gives up everything by the close, the marginal buyer is not the problem. The discount rate is.

The plumbing is visible. A $25 billion 30-year Treasury auction on the 13th cleared at 5.22%, the highest since 2001, and selling followed [s1c10]; the market has since added another 10 basis points on top of that clearing yield ^[3]. Japan's 10-year spiked to 2.930% in session, the highest in about 30 years, raising the prospect that Japanese institutions repatriate into domestic bonds and push U.S. long yields higher still [s1c11]. U.S. government debt has passed $40 trillion [s1c12]. The head of Meritz Securities' research center put the transmission plainly: as Big Tech capital spending has expanded beyond free cash flow into debt financing, its sensitivity to interest rates is far higher than in the past [s1c13].

Which brings us to Nvidia. It signed a deal to provide up to $105 billion, about 149 trillion won, in residual-value guarantees for the Ports Pike campus in Ohio being built by SB Energy for OpenAI, conditional on exclusive supply of Nvidia AI chips [s1c14][s1c15]. The guarantee covers only the initial 4.25GW, with possible additional support for the remaining 3.75GW [s1c16]. At the same rate per gigawatt, full coverage of 8GW would imply roughly $198 billion of guarantees ^[4]. Nvidia says the project could involve about 1.5 million GPUs and generate $150 billion to $200 billion in revenue [s1c17]; the same briefing also cites a figure of about $600 billion in revenue through 2030, and those two numbers are not reconciled [s1c18]. Against the smaller pair, the guarantee equals 53% to 70% of the revenue it is meant to unlock ^[5], or about $70,000 of exposure per GPU ^[6].

Jensen Huang directly rebutted the circular-financing controversy [s1c19]. Critics counter that even without Nvidia putting up cash, the structure effectively guarantees its own chip sales [s1c20]. The sharper objection is the one Jeffrey Gundlach has pressed on AI chip lifespan [s1c21], because a residual-value guarantee is a written position on exactly that: Nvidia now owns the depreciation curve it previously only sold into.

Two events are being treated as the watershed for both semiconductor sentiment and rates: Nvidia's earnings and next week's Jackson Hole meeting [s1c22]. Keep a third marker on the desk. KB Securities has nominated a U.S. 10-year yield of 5.0% to 5.3% as the boundary for judging whether the AI bubble breaks, and argues the epicenter of risk sits with capital suppliers such as financial institutions rather than Big Tech itself [s1c23].