Top Strategist: Japan Just Unleashed a Historic Yen Intervention. Here’s What Comes Next

Masahiko Loo, Senior Fixed Income Strategist at State Street Investment Management, framed last week’s US-Japan currency intervention as a turning point in how policymakers can combat yen weakness without destabilizing the world’s largest bond market. Speaking on Bloomberg on August 3, Loo argued that coordination between Tokyo and Washington signals a deliberate shift away from selling U.S. Treasuries to prop up the Japanese yen.

Why Japan’s Currency Defense Threatened the US Treasury Market

Loo explained that the big fear is that Japan will sell US Treasuries to rightsize its currency: “Whenever it intervenes, what Japan does is they have to sell something to intervene and buy yen and prop up yen… and sell US dollars. And the fastest way is to sell US Treasuries. I think that creates some funding problem in the US market,” he said. With intervention sizes typically ranging from $35-$50 billion dollars, forced Treasury sales at that scale can jolt a market already digesting elevated yields.

The 10-year Treasury yield closed at 4.68% on July 30, 2026, sitting near the 12-month high of 4.71% hit on July 23. The current level sits in the 98.8th percentile of the trailing 12-month range. Any incremental supply from foreign official sellers lands in a market where funding conditions are already tight, and the Fed has held its target rate at 3.75% since December 10, 2025.

The Fed’s Secret Weapon for Preventing a Treasury Sell-Off

The Foreign and International Monetary Authorities (FEMA) repo facility allows the New York Fed to lend dollars to foreign central banks in exchange for pledged Treasuries.

“A FEMA repo is essentially a repo that any central bank with a repo line/swap line with the New York Fed can… tap to get US dollar funding by pledging US Treasuries that they hold. So this is essentially being able to intervene in the market without really physically selling US Treasuries,” Loo explained. The facility was previously deployed in 2019 to calm short-term funding stress.

Loo credited both the US and Japan for reaching for the tool early. “It’s a very smart move from [the] US, Bessent, and also Katayama to actually tap on the wire to signal… they will be able to use the FEMA repo. This is more of a signaling effect,” he said.

Why State Street Believes USD/JPY Has Already Peaked

Loo believes the dollar-yen pain trade has flipped direction. “I think we have probably seen the top in dollar-yen at 164ish. And now the next level to watch is actually not a weaker yen, but a strengthening. I think 155 is the level that the market is watching,“ he said. On Monday, USD/JPY traded at 156.77, down substantially from the 164 level.

Volatility indicators show a similar shift in tone. The VIX spiked to 20.66 on July 29 before retreating to 17.09 on July 30, a same-day decline of 17.3%. The 10-year-minus-2-year Treasury spread has re-steepened to 0.47% as of July 31, up 30.6% over the past week, suggesting the bond market is pricing in less tail risk from a disorderly reserve unwind.

The next move in USD/JPY will show whether last week’s intervention established a durable ceiling near 164. A continued decline toward Loo’s 155 target would strengthen that case. A rebound toward 160, however, would suggest that the intervention delivered only a temporary pause in the yen’s longer-term slide.

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