Quantum Si Inc Class A (QSI) returns
Quantum Si returns over 5 years
$1,000 invested in Quantum Si five years ago was worth $181.14 at the close on October 30, 2026, with dividends reinvested: an average return of -28.9% a year. The same $1,000 in the S&P 500 (SPY) became $1,760.
Total return by period
| Period | Total return | A year, on average | $1,000 became | S&P 500 (SPY) |
|---|---|---|---|---|
| 1 month | +36.4% | — | $1,364 | -0.9% |
| 3 months | +102.8% | — | $2,028 | +2.1% |
| Year to date | +32.7% | — | $1,327 | +11.7% |
| 1 year | -28.1% | — | $719.21 | +12.4% |
| 3 years | +24.8% | +7.7% | $1,248 | +88.5% |
| 5 years | -81.9% | -28.9% | $181.14 | +76.0% |
Quantum Si return by calendar year
| Year | QSI | S&P 500 (SPY) | Difference |
|---|---|---|---|
| 2026 to date | +32.7% | +11.7% | +21.0% |
| 2025 | -59.3% | +17.7% | -77.0% |
| 2024 | +34.3% | +24.9% | +9.4% |
| 2023 | +9.8% | +26.2% | -16.4% |
| 2022 | -76.7% | -18.2% | -58.6% |
| 2021 | -22.5% | +28.7% | -51.2% |
Past returns do not predict future returns. Returns are computed from our daily closes, adjusted for splits and with dividends reinvested on their ex-dates; taxes and trading costs are left out.
See also: QSI financials
No forecast, no recommendation. This page describes Quantum Si Inc Class A from published data; it is not advice to buy, sell or hold any security.
Figures as of the close on Oct 30, 2026 unless a row says otherwise. Prices are split adjusted; returns include dividends reinvested. Data may be delayed. See the disclaimer and how TrendArc works.