The won's old link to the yen and the IIF's new driver are different kinds of things, and the trade now rests on which one is doing the work. The won's old link to the yen was a relative-price belief: Korea competes with Japan in export markets, so a cheaper yen bid the won down by inference [3]. The IIF's replacement driver is cash with a settlement date, namely export proceeds parked offshore in dollars and converted into won because Samsung Electronics and SK hynix need won to pay for domestic fabs [4]. The first can hold for years without a dollar changing hands, while the second shows up in somebody's FX book.
Take the policy leg first, because the arithmetic is checkable: a 0.25 point hike in August that lifted the base rate to 3.00% puts the pre-August setting at 2.75%, and July's increase came before that [8][14]. Governor Shin Hyun-song said the exchange rate has stabilized but remains high by historical standards, and that pre-emptive policy leaves room for further appreciation [9]. Read it as allocation rather than commentary: the central bank is not spending anything to cushion exporters' translated earnings, at the same moment the IIF has exporters' own treasuries pushing the won the same direction [4][9].
Then the part that matters for anyone marking a book. The IIF concedes that even without a full-scale shift in conversions, the market is already pricing the prospect of stronger won demand [5]. So 1,372.5 on the 28th, a 13-month high [10], embeds an expectation about two companies' cash management, while the roughly 10%-of-GDP current account surplus the IIF projects through next year [6] is backdrop, not engine, because that surplus was widening during the years the won was weak [2]. The destination is described as pre-Covid levels with no number attached [7], and that vagueness is itself hard to hedge against.
There are a few ways this reading could be wrong. Fabs get funded from offshore dollar cash or dollar borrowing, the repatriation never scales, and the market has already paid for a flow that does not arrive. Or the other two drags the IIF lists alongside the yen, residents buying foreign assets and foreigners net selling Korean stocks [2], reassert themselves, and note that what the Bank of Korea reported was easing outflows from foreign equity funds rather than inflows [11]. Or the external leg turns, which is the caveat one FX specialist quoted in the report made explicitly about U.S. monetary policy and overseas investment flows [12].
My view, held loosely: the correlation break matters more than the level. Anyone who let the yen do part of the work in a Korea hedge had their basis repriced in July [1], and the replacement variable is two corporate treasury committees, which is thinner to underwrite than a trade balance. The falsification is clean. If the yen weakens further and the won follows it down while chip capex proceeds on schedule, then July was simply dollar softness, not a new story [11].
