Shares of Personalis (NASDAQ: PSNL) are experiencing a significant pre-market plunge of 17.98% on Wednesday, continuing the downward trend that began in after-hours trading on Tuesday. The sharp decline comes in the wake of the company's third-quarter 2025 financial results release, which revealed mixed performance and disappointing forward guidance.

While Personalis managed to beat revenue expectations for Q3, reporting $14.495 million against an analyst consensus of $13.3 million, the figure still represents a substantial 44% year-over-year decline. The company's net loss for the quarter stood at $21.652 million, or $0.24 per share, which was better than the expected loss of $0.28 per share. However, these results were overshadowed by the company's weaker-than-anticipated fourth-quarter guidance.

The primary catalyst for the stock's plummet appears to be Personalis's disappointing Q4 outlook. The company forecasts Q4 revenue between $15.7 million and $20.7 million, falling well below the consensus estimate of $21.8 million. Additionally, Personalis revised its full-year 2025 revenue projection to a range of $68.0 million to $73.0 million, further fueling investor concerns about the company's near-term financial performance. Despite reporting a 364% year-over-year growth in clinical test volume, driven by increased adoption of its NeXT Personal platform, this positive news was not enough to offset the negative sentiment surrounding the company's financial outlook.