Short sellers have piled into MUU at a pace rarely seen in leveraged ETF markets. Short interest jumped from roughly 1 million shares on July 13 to 14.3 million shares on July 15 — a 4,895% surge in one week, pushing estimated short interest to 355% of float.
That number is not a typo. For a 2x leveraged single-stock ETF tracking Micron Technology, short interest exceeding the entire float reflects the mechanics of leveraged product creation and redemption. But the scale of the move in a matter of days signals something unusual is happening in the borrow market.
The borrow market tells the clearest story. Availability — the ratio of shares still available to lend relative to shares already borrowed — sits at just 5.8%. That means roughly one share remains available for every seventeen already out on loan. The lending pool is effectively exhausted.
This tightness has been persistent. Availability dropped below 12% on July 10 and has stayed there. On July 7 it briefly touched 1.9%. The 52-week low is 0%, hit multiple times between June and mid-July.
Despite that tightness, cost to borrow has fallen sharply. CTB dropped to 1.96% on July 15, down 53% over the prior week. That divergence — maximum borrow stress with falling borrowing cost — suggests the demand for new shorts has cooled even as existing positions remain locked in.
MUU tracks twice the daily return of Micron Technology. The ETF is down 28% over the past week and 45% over the past month. That sustained decline reflects Micron's weakness amplified through the 2x daily reset mechanism.
Short interest exceeding 100% of float is structurally possible in leveraged ETFs. Creation and redemption activity can result in short positions that exceed the technically outstanding share count. Still, the 1,318% single-day jump on July 15 — from ~1 million shares to 14.3 million — is an extreme single-session move.
The ORTEX short score stood at 46.6 as of July 15, down sharply from 65.1 on July 13. That drop reflects the changing composition of signals rather than a straightforward easing of pressure.
Options positioning is relatively calm by comparison. The put/call ratio sits at 0.82 on July 16, near but below the 52-week high of 0.97. The PCR z-score of 0.38 indicates modest bearish skew — elevated but not extreme.
See the live data behind this article on ORTEX.
Open MUU on ORTEX →ORTEX Market Intelligence content is generated by AI from a snapshot of ORTEX's proprietary data. Content is informational only and does not constitute investment advice.
