ASTS: Short Interest Jumps 10% in a Week as Borrow Stays Locked

AST SpaceMobile enters the back half of September with its most striking weekly short-building episode in months — bears added roughly six million shares in a single week while the stock dropped 4%, and the borrow market shows no sign of loosening.

The short interest surge is the headline number. Bears pushed positions to 64.8 million shares, or 23.3% of the free float — a 10.7% week-on-week jump that represents the most aggressive single-week build since the August peak. That's a meaningful step-change: through most of August, short interest ground higher at a measured pace of one to two percent a week. The acceleration happened in a clean window — shares jumped from 58.7 million to 64.9 million between September 7 and September 10 before flattening. The previous note flagged availability rebounding to 14.6% on September 1 as a sign of breathing room. That room has closed again. Availability is back to 6.2% — tight, though notably off the near-freeze of 1.7% seen on September 4. The 52-week low of 0.31% shows how much tighter things have been, and the current direction is still compressing. Borrow cost is subdued at 1.21% and has barely moved for weeks, reinforcing what was noted last time: this is a structural scarcity story, not a cost-driven squeeze. The ORTEX short score has crept to 72.9, its highest reading in the recent history shown here, and both the short-score rank and utilization rank sit at the 1st percentile of the universe — effectively as extreme as it gets.

Options positioning tells a different story, and the contrast is worth naming. Despite the aggressive short-building in the underlying, the put/call ratio is 0.46 — almost exactly in line with its 20-day average and well below the 52-week high of 0.67. Options traders are not rushing for downside protection. That divergence matters: the short-sellers are expressing a view through the stock-borrow market, not the derivatives market, suggesting a more deliberate, structural short rather than panic hedging ahead of a near-term catalyst. The stock itself fell 4% on the week to $59.86, down 16% over the past month — so shorts have price momentum working in their favour for the first time in a while.

The Street remains divided, but the weight of analyst opinion is skewed bullish on price targets that sit well above the current price. Berenberg initiated coverage at Buy with a $92 target in early September, the most recent addition to a group that includes Piper Sandler at $98 Overweight and Cantor Fitzgerald at $90 Overweight. UBS, maintaining Neutral, trimmed its target to $78 after the last earnings print on August 11. The consensus mean sits near $78 — implying around 30% upside from current levels. The bull case centres on ASTS's IP portfolio, growing telco operator demand, and the sheer scale of the low-Earth-orbit broadband opportunity. Bears counter with the cash burn: EV/EBITDA is deeply negative, the Piotroski F-Score is weak at 3, and every incremental satellite deployment carries execution and regulatory risk. The EPS surprise factor score of 92 is a genuine positive — the company has consistently beaten estimates — but it is hard to reconcile with a negative earnings yield and a price-to-book of 12x as the float continues to be diluted.

The ownership register adds one more layer of complexity. AT&T and Vodafone Ventures both hold strategic stakes and both carry Schedule 13D filings — meaning they disclosed active, not passive, investor intent. Rakuten Mobile, another 13D filer, trimmed its stake from 7.2% to 5.3% in its last disclosure in May. These strategic holders anchor the register but also mean the float dynamics are not purely driven by institutional flows; partner stakes that reduce could add supply. Separately, director Adriana Cisneros made open-market purchases totalling roughly $620,000 on August 31 — three tranches, no 10b5-1 plan, at prices around $57-59. The net 90-day insider flow is negative overall (dominated by earlier sales), but that buying at current levels from a board member is worth flagging as a contrast signal against the short-building. The 90-day FINRA-reported figure of 64.1 million shares short with 7.25 days to cover confirms the picture is not academic — it would take over a week of average volume to unwind the current position.

Closest peer IRDM gained 0.7% on the week and GSAT added 0.6%, while ASTS dropped 4% — the sector was broadly flat, making the underperformance specific to ASTS rather than a sector-wide move. Next earnings are flagged for November 10, giving shorts roughly eight weeks of runway before the next scheduled forced reckoning. What to watch is whether the fresh short positions added this week hold through any further price weakness, or whether the borrow pool tightens back toward the near-freeze levels seen on September 3 and 4 — at which point new short demand would face a genuinely constrained lending market.