BillionToOne enters the week after a sharp 11% single-day rally on May 6, but short sellers are not backing down — making this stock one of the most pressured borrowing situations in healthcare right now.
The lending market tells the most urgent story. Short interest has climbed 54% over the past month to 2.02 million shares, now accounting for 8.7% of the free float. More striking is what is happening to borrowing conditions. The cost to borrow has tripled from roughly 10–40% APR in late March to 128% today — and availability has collapsed to just 0.14% of short interest. Every share in the lending pool is already out on loan; there is essentially nothing left for new short sellers to borrow. The ORTEX short score, at 84.5, has crept to its highest reading of the past two weeks and has held above 82 without interruption since late April. This is a borrow market under maximum stress.
Options traders, by contrast, are leaning the other way — and sharply so. The put/call ratio dropped to 0.44 on May 5, more than two standard deviations below its 20-day average of 0.65. That is the most bullish options positioning of the past year and a clear pivot from March, when the PCR was running above 1.6. Call demand has surged even as short sellers are piling in on the stock-loan side. The divergence between heavily-stressed borrow conditions and aggressively bullish options flow is the defining tension on this name right now.
The analyst community has grown more cautious without abandoning a broadly constructive view. After the March 4 earnings report — which sent the stock down 13% in a day and 19% over five sessions — Guggenheim, Wells Fargo, and BTIG all trimmed price targets, with Guggenheim most recently cutting to $100 from $120 on March 30. The mean target among covering analysts is $116.71, implying roughly 46% upside from current levels near $80. That is a generous spread, though it reflects targets set in the wake of a disappointing quarter rather than a fresh consensus. The bull case centres on UNITY prenatal test growth and the pending MRD oncology launch; the bear case flags reimbursement risk, NIPT market saturation, and execution uncertainty on the pipeline. The P/E multiple is running at 125x, up roughly 9 points on the week, while EV/EBITDA stands near 51x — pricing in substantial growth that the company has yet to fully deliver.
On the institutional side, several new names built positions at year-end 2025. Baillie Gifford initiated a stake of 1.27 million shares, Civilization Ventures took a fresh 1.1 million, and Neuberger Berman added 700,000 shares through Q1 2026. T. Rowe Price and JP Morgan Asset Management both reported new holdings as of March 31. That cluster of fresh institutional buying through Q4 and Q1 adds one more layer of contrast to the record short positioning in the lending market — institutions accumulating while short sellers simultaneously exhaust the borrow pool.
The next earnings event is June 9. With availability at near-zero, cost to borrow still above 100%, a PCR near its 52-week low, and a stock that just bounced 11% off a post-earnings lows, the key variable to watch is whether call-side demand can sustain price above the $80 level — or whether borrow-exhaustion translates into a squeeze dynamic before the next quarterly print.
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