Three signals converged on BLOK within 24 hours. Short interest, cost to borrow, and options positioning all moved in the same direction — and the pace of change is the story.
Short interest in the Amplify Blockchain ETF has risen 167% in one week. It now stands at 2.55% of free float. That is still a low absolute level. But the velocity is notable. Shares short climbed from roughly 184,000 on June 8 to 492,000 by June 16 — nearly a tripling in eight trading days.
One month ago, short interest sat above current levels before declining sharply through late May. The current build is a reversal of that unwind, concentrated almost entirely in the past two weeks.
Availability has dropped sharply. One week ago it stood at over 600%. Today it sits at 81% — meaning roughly one share remains available for every 1.25 already borrowed. That is a steep tightening. The 52-week low for availability on BLOK is 0.47%, recorded earlier this year, so there is room for further compression.
Cost to borrow rose 132% over the same week to 1.30%. That remains a low absolute rate. But the directional move matches the availability squeeze — fewer shares left in the pool is beginning to push up the price of borrowing.
Here the picture diverges. The put-call ratio stands at 0.34 — the highest in 20 days and roughly 1.6 standard deviations above the 20-day mean. A low PCR signals call dominance. Traders are buying calls, not puts. The 52-week low for the PCR is 0.20, so this reading is elevated relative to recent norms but far below the historical high of 0.91.
That contrast is the tension in this setup. Short sellers are adding exposure and paying more to borrow. Meanwhile, options market participants are leaning toward calls. Both sides are active — the market is not in agreement.
The key dynamic to watch: availability has tightened fast. If short interest continues to build at the current pace, the remaining borrow pool will come under further pressure — and cost to borrow will follow.
See the live data behind this article on ORTEX.
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