Why this matters: Short interest in the EWJ iShares MSCI Japan ETF surged 53% in a single week. Cost to borrow has nearly doubled over the past month. Options traders are loading puts at an elevated rate. Three signals are pointing the same direction.
SI hit 4.8% of free float as of September 24. That's up from around 3.1% just one week ago. Over the past month, short positions have grown 64%.
The absolute level is modest for an ETF. But the pace of accumulation is the story. Short shares jumped from roughly 5.9 million to 9.1 million in five trading sessions. That kind of velocity in a large, liquid ETF is unusual.
Cost to borrow stood at 0.53% on September 4. It now sits at 1.28% — more than double in three weeks.
Availability has dropped sharply. One week ago, availability stood at over 1,000% of short interest — a deeply loose lending market. It has now fallen to 360%. That's still in normal territory, but the direction is stark. Availability has tightened by 62% in a week. If short demand continues growing at this rate, the borrow market could move into genuinely tight territory quickly.
The put/call ratio sits at 2.11. The 20-day average is 1.80. That puts the current reading 1.73 standard deviations above the mean — elevated, though not extreme.
Put-heavy positioning has been building since mid-September. The PCR was 1.67 on September 16. It crossed 2.0 on September 22 and has held above that level through this week. Traders are paying up for downside protection on Japanese equity exposure.
BlackRock raised its stake to 12.5% of shares as of August 31, adding nearly 9.5 million shares in the latest reported period. That's the largest single holder move in the register. It reflects BlackRock's role as the ETF's own issuer rather than a speculative position, but it does underscore how concentrated top-tier ownership remains.
JPMorgan trimmed slightly. UBS Asset Management cut its position by 650,698 shares in the June quarter.
What to watch: Whether availability continues tightening toward the 50–200% range that signals a genuinely stressed lending market — and whether the PCR z-score pushes past 2.0 on continued put accumulation.
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