Key Highlights

  • Quantum-Si (NASDAQ:QSI) rose 105.45% over one month in published market data as of October 28, 2026, including 46.12% in the latest week and 133.60% over three months.
  • Interim data released on September 28, 2026 showed the Proteus platform delivering a median 30 times more alignments per single-chamber run than the commercial Platinum Pro system.
  • The false discovery rate was 1.36% versus 6.58% for Platinum Pro, a 4.8-fold reduction, and the company expects a Proteus launch in the second quarter of 2027.
  • Cash and short-term investments were about USD 111.7 million in the latest reported quarter, against a quarterly net loss near USD 23.5 million at Quantum-Si (NASDAQ:QSI).

What Moved the Stock

Quantum-Si (NASDAQ:QSI) develops protein sequencing instruments, and its monthly gain began after a September 28, 2026 release of interim data for Proteus, its next-generation platform, presented by CEO Jeff Hawkins at World HUPO in Singapore on September 29. The developmental kit detects 18 amino acids, and the company says the system is not yet fully optimized. In a control peptide study of four runs per platform, Proteus produced a median of 30 times more alignments and identified all six control peptides in every run. Late September closes were reported near USD 0.80 to USD 0.96, so the move started from a sub-USD 1 base. The company reported the interim data in a press release dated September 28, 2026, ahead of the presentation in Singapore the following day.

Proteus Versus Platinum Pro

Against the commercial Platinum Pro, Proteus identified 1.6 to 2.0 times more peptides in protein mixtures and detected all 24 proteins in a new panel versus an average of 20.3 for Platinum Pro. A projected four-chamber run could deliver about 60 times more alignments than a two-chamber Platinum Pro run, though that is a projection, not a measured result. Management expects the commercial kit to detect all 20 amino acids at launch in the second quarter of 2027. The company also reportedly regained compliance with the Nasdaq USD 1.00 minimum bid rule after ten consecutive closes above USD 1.00, as of October 20. Cysteine and histidine were detected only on Proteus, which the company presents as evidence that the new chemistry reaches amino acids that the older instrument misses. Proteus was also reported to detect 19 of 20 amino acids.

Risks and Next Steps

The numbers are interim and company-generated, with a small sample. Revenue was only about USD 344,000 in the last reported quarter, so the valuation rests on a launch at least two quarters after the data. Cash of about USD 111.7 million funds roughly four to five quarters at the recent pace, simple arithmetic on two reported numbers, and an equity raise could follow. A third quarter business update and call is scheduled for November 5, 2026. Quantum-Si (NASDAQ:QSI) remains volatile after a 105.45% month. Management is targeting full 20 amino acid detection by the end of 2026, and any slip would push back the launch case. The shares are also priced near USD 1.70, so a return below USD 1.00 would reopen the Nasdaq bid question.

Where Things Stand

Quantum-Si (NASDAQ:QSI) gained 105.45% because interim Proteus data on September 28, 2026 showed large gains over Platinum Pro and a second quarter 2027 launch plan, and because the stock then regained the USD 1.00 Nasdaq minimum bid. That is a credible technical catalyst but not yet a revenue story, with quarterly sales near USD 344,000. The next tests are the November 5, 2026 business update, kit progress toward 20 amino acids and any financing.