The writer is the Rene M Kern professor of practice at Wharton School, chief economic adviser at Allianz and chair of Gramercy Funds Management
For much of the past year, both the real economy and financial markets have operated under the expanding shadow of US economic statecraft.
This has ranged from more aggressive industrial policy to tariff escalation and export restrictions as well as expanding moral suasion. As a result, resource allocation and price discovery in markets have increasingly drifted from commercial and economic logic, influenced more by geopolitics, national security and domestic political expediency.
One of the most striking features of this geoeconomic era is the US Treasury department’s growing willingness to intervene directly in financial market pricing. One such intervention, aimed at stabilising the Argentine peso, achieved its objective. A second, intended to suppress long-term Treasury yields and damp bond market volatility, has stumbled. The jury is out on a third initiative to bolster the Japanese yen.
Taken together, these three examples provide critical lessons on when unconventional direct market intervention can succeed — and importantly when the credibility of this tool can be eroded.
In Argentina, a depreciating peso fuelled domestic inflation and undermined support for President Javier Milei ahead of key elections. The US Treasury stepped in by providing a dollar swap line — an agreement to exchange currencies — to a strong ally of President Donald Trump.
Framed by Treasury secretary Scott Bessent as an effort to contain regional systemic risk, markets saw the move more as a political lifeline. The intervention succeeded. The peso stabilised and inflation dynamics moderated. The success was aided by the fact that the Argentine foreign exchange market is small and Milei’s policy stance is generally supportive of the currency.
A subsequent attempt by the US Treasury to manage domestic sovereign yields has proved far less effective. Reacting to a sharp rise in yields, Bessent announced that the Treasury would step up its buyback programme for long-dated bonds and consider other measures, if needed. The rationale was to smooth out “disorderly” moves during illiquid summer conditions. Many market participants, however, viewed it as an attempt to suppress mortgage rates ahead of the US midterm elections. Over the weeks that followed, yields across the curve continued to surge, rising about 0.5 percentage points.
The US Treasury market is immense, globally integrated, and driven by powerful structural dynamics that cannot easily be overcome. They include rising government bond issuance to fund a fiscal deficit of 6 per cent of GDP, the refinancing of maturing debt at much higher rates, and heavy corporate borrowing to fund tech-related investments. This is occurring as demand from some historically reliable buyers is diminishing.
The experience in the currency markets with the Japanese yen falls between these two extremes. The intervention was framed as mitigating global financial instability and protecting US trade from an excessively cheap currency. Yet markets quickly recognised another motive: the need to minimise the risk of higher US yields from Japan’s sales of Treasuries as it sought to raise dollars to defend the yen. While the yen initially appreciated, it has slipped back since. Unsurprisingly, the tactical intervention has struggled to overcome fundamental issues in Tokyo’s monetary, fiscal and structural policy mix.
When asked in an Axios interview about the interventions, Bessent declared: “The house doesn’t win every hand. The house plays percentages.” This referenced his earlier claim — “I am the house now” — evoking the casino saying that the house always comes out ahead. Viewing sovereign market interventions through the lens of a casino operator risks misdiagnosing the factors at play. The power of policymaker interventions in pricing depends largely on market size and the state of the underlying fundamentals.
Market intervention is meant to be a “circuit breaker” to interrupt non-fundamental, self-reinforcing market dynamics or severe liquidity stress. When deployed sparingly during genuine dislocations, it carries immense signal value and potency. But when used repeatedly to try to counter underlying market fundamentals, achieve short-term political objectives, or manage prices in deep, liquid global asset classes, its effectiveness can diminish. Using it as a routine policy lever rather than an emergency safety valve risks turning a market stabiliser into a source of moral hazard and deeper volatility.