BTC Trust Shorts Nearly Double in a Week as Borrow Costs Ease

BTC, the Grayscale Bitcoin Mini Trust, is showing an unusual split this week: short interest is building at its fastest pace in months while the cost to maintain those positions is actually falling.

The short position has nearly doubled over the past month and accelerated sharply this week. Shares short rose 58% over the past seven days to reach 796,500, taking short interest to 0.73% of the free float. That is still a low absolute level, but the pace of accumulation is the story: shorts have grown 97% since late September. The last note, filed October 14, flagged short interest at 0.49% of float and declining. The direction has reversed materially since then, with new positions added on each of the past five trading days.

What makes the build unusual is that borrow costs are moving the wrong way for new shorts to be rational pain. Cost to borrow has fallen 21% over the past week to 0.80%, well below the 1.5% peak seen on October 9. Availability is essentially limitless: more than 23 million shares are available to lend, giving an availability reading above 3,499%, meaning there are roughly 35 shares available for every one already borrowed. The lending market is under no pressure whatsoever. Shorts are adding positions into a cheap and open borrow market, not being squeezed out of one.

Options positioning reinforces the bullish lean of most participants. The put/call ratio has drifted lower to 0.25, below its 20-day average of 0.27 and near the 52-week low of 0.23. That puts the ratio almost a full standard deviation below normal, reflecting a market where calls comfortably outnumber puts. The setup in options is the opposite of the message from the rising short book: one side is adding downside exposure while the other is positioned for further gains.

The trust itself closed at $36.48 on Tuesday, up 0.9% on the day but still down 0.8% on the week. With no earnings calendar, no analyst coverage, and a NAV anchored entirely to Bitcoin's spot price, the fundamental driver sits outside this product entirely. The ORTEX combined score is a modest 27.7, reflecting no particular momentum or quality signal from the trust itself.

The divergence between a rapidly growing short position and a calm, cheap borrow market is the data point worth watching: whether short interest continues to build at this pace, or whether the week's accumulation proves a temporary positioning shift ahead of any move in the underlying Bitcoin price.