Rtw Investments 13F: Adds $15M to Castle Biosciences (CSTL) Stake

RTW Investments Expands Castle Biosciences Holding

RTW Investments grew its stake in Castle Biosciences, Inc. (NasdaqGM: CSTL) during the reporting period, adding 643,098 shares to its portfolio. The addition marked a 30.4% increase from the prior period, bringing the fund's total ownership to 2,758,335 shares. Based on the market valuation at the time, the block of shares carried a value of approximately $65.8 million. This Form 13F filing captures institutional holdings as of the specified date and may not reflect the fund's current share count today.

Castle Biosciences Stock and Market Context

Shares of Castle Biosciences traded near $23.85 ahead of this reporting cycle. The stock moves within a 52-week range spanning from a low of $17.72 to a high of $44.28. Its 50-day moving average sits at $30.31, while the 200-day moving average rests closer to $29.23. Because the company generated negative earnings per share of $0.64 over the trailing period, it does not carry a meaningful forward P/E ratio.

Recent Insider Transactions at Castle Biosciences

Company insiders have made adjustments to their personal share counts recently. On June 16, 2026, Chief Operating Officer Kristen Oelschlager sold 8,587 shares at an average price of $20.71, totaling $177,836.77 in a transaction executed under a Rule 10b5-1 trading plan. Earlier on June 15, 2026, Chief Executive Officer Derek Maetzold picked up 550 shares at a price of $2.39 each, for a total value of $1,314.50.

Wall Street Analyst Updates

Financial firms continue to evaluate the diagnostic stock with varying price targets. On August 3, 2026, BTIG maintained its Buy rating on the stock while lifting its price target from $40.00 to $44.00. Earlier on June 25, 2026, Roth Capital initiated coverage on the company with a Buy rating and a $40.00 price target. Across the broader analyst community, the stock holds a consensus target mean price of $44.00 based on nine tracked opinions.

Inside Castle Biosciences Diagnostics

Castle Biosciences operates as a molecular diagnostics provider focused on creating test solutions for dermatologic cancers, Barrett's esophagus, and other conditions. Its specialized genomic tests help physicians assess metastatic risk and guide treatment decisions for patients dealing with complex skin and gastrointestinal diseases. Institutional backing from funds like RTW Investments aligns with ongoing interest in the firm's specialized diagnostic pipeline.

Looking Ahead for the Diagnostics Firm

Market participants will monitor upcoming regulatory filings to see if RTW Investments modifies its position further. The company's next scheduled financial results are expected around November 2, 2026. Because 13F filings look backward, investors should note that these disclosed figures reflect historical positioning rather than real-time trades.