Won strengthens for a fifth session as exporters sell dollars into a firmer greenback

The move was small, and its direction was the odd part. The won gained 1.9 won from a previous close of 1,340.4, about 0.14% ^[18]. The dollar index rose 0.175 point to 102.288 the same day, roughly 0.17% against six major currencies [c8, d2]. Against that basket the won outperformed by about 0.3 percentage points ^[20].

Scale explains most of it, or rather the scale of the surplus does, if exporters convert it. Yonhap put the day's foreign equity sale at about $1.5 billion ^[3]. Set against August's $46.11 billion surplus ^[11], the sale equals about 3% of one month ^[21], and selling at that pace would take roughly 31 sessions to match it ^[22]. With the surplus above $40 billion for three straight months, the total since June exceeds $120 billion ^[23].

A surplus is an accounting total. It becomes demand for won only when exporters sell their dollars. Seoul Economic Daily reported that they did, saying strong semiconductor exports kept a lid on the dollar-won rate as exporters converted proceeds ^[6]. The same report named a second seller, foreign investors in dollar futures ^[7]. It said the won rose because the two together exceeded market demand for dollars ^[8], but it did not split that total between them. Yonhap described the gain as coming amid broad dollar strength, with Fed minutes signaling inflation risks ^[9].

In my view the exporter explanation is right about direction, given the size of the surplus. The stronger claim, that chip conversion dominates the won, rests on that size alone. Exporters are also converting while holding dollars pays well: U.S. 10-year yields above 5% ^[13] are a return they give up on every dollar they sell. Samsung's profit jump implies a year-earlier operating base near 12.2 trillion won ^[24]. Seoul Economic Daily said strong exports and improving earnings raised expectations that dollar selling could continue for some time ^[14].

If conversion continues, the won tests the 1,334 range that market participants cite as the next support, 3.9 won from the close and set by the year's best of 1,334.6 on Sept. 9 [c15, d8]. A Fed increase, a possibility the September minutes reaffirmed for this year ^[10], would lift yields and push the dollar-won rate back above 1,340. A longer run of foreign equity selling is the third route.

The exporter thesis has a plain failure test. If the next current account release stays above $40 billion and the won still drifts back above 1,340, exporters were not the marginal seller on Oct. 8, and the support came from foreign futures sellers.