Rtw Investments Adds $15M in Castle Biosciences, Inc. ($CSTL)

RTW Investments has increased its stake in Castle Biosciences, Inc. (NasdaqGM: CSTL) by 30.4%, according to its latest 13F filing with the SEC. The investment firm added 643,098 shares, bringing its total holdings to 2,758,335 shares valued at approximately $57.1 million as of the reporting period.

What Changed in RTW Investments's Castle Biosciences Position

RTW Investments boosted its position in Castle Biosciences from 2,115,237 shares to 2,758,335 shares, marking an increase of 643,098 shares or 30.4%. The value of this position is now about $57.1 million, demonstrating the firm's increased confidence in the company's prospects.

Other Institutional Activity in Castle Biosciences

Other major funds have also adjusted their positions in Castle Biosciences. BlackRock, Inc. reduced its holdings by 122,300 shares, ending with 2,982,946 shares worth approximately $73.2 million. Principal Financial Group Inc trimmed its position by 37,767 shares, holding 1,769,877 shares valued at $43.5 million. Portolan Capital Management, LLC cut its stake by 379,180 shares to 1,350,283 shares valued at $33.1 million. Meanwhile, Vanguard Capital Management LLC initiated a position with 1,177,522 shares valued at $28.9 million.

Castle Biosciences, Inc. Stock Down 28.8%

Shares of Castle Biosciences are trading around $20.70. The company has a market capitalization of about $627.8 million. It currently has no meaningful P/E ratio due to negative earnings, with a forward P/E of -22.26. The stock's 52-week range is between $14.59 and $44.28, with a 50-day moving average of $22.27 and a 200-day moving average of $28.77. Castle Biosciences maintains a strong liquidity position with a current ratio of 6.75 and a quick ratio of 6.26.

Recent Earnings

Castle Biosciences reported revenue of $339.92 million, reflecting a slight decline of 4.9% from the previous year. The company posted a negative net margin of 3.78% and a return on equity of -2.85%. The next earnings report is expected on August 3, 2026.

Insider Buying and Selling at Castle Biosciences, Inc.

Recent insider activity at Castle Biosciences included several transactions. On June 1, 2026, CEO Derek Maetzold sold 6,214 shares and bought the same number at an average price of $2.39, and later sold 9,836 shares at $20.86 under a planned sale. Other insiders, including Ellen Goldberg, Rodney Cotton, and Kim Caple, each purchased 11,766 shares on May 28, 2026.

Analysts Set New Price Targets

Analysts have shown bullish sentiment towards Castle Biosciences. On May 13, 2026, BTIG maintained its "buy" rating with a $40 price target. Baird also reiterated its "buy" rating with a target of $43 on May 7, 2026. Canaccord Genuity kept its "buy" rating with a $40 target on April 20, 2026. The consensus target price among analysts is $44, based on eight opinions.

About Castle Biosciences

Castle Biosciences, Inc. is a molecular diagnostics company based in Friendswood, Texas. It focuses on providing diagnostic and prognostic testing solutions for dermatologic cancers, Barrett's esophagus, atopic dermatitis, and uveal melanoma. The company, led by CEO Derek J. Maetzold, serves dermatology and gastroenterology markets with products like DecisionDx-Melanoma and TissueCypher.

Bottom Line

RTW Investments' significant increase in its stake in Castle Biosciences highlights the firm's confidence in the company's future. Investors keep a close eye on 13F filings like these to gauge institutional sentiment, but it's important to remember that these filings are backward-looking and may not reflect current holdings. Castle Biosciences continues to be a company of interest due to its innovative diagnostic solutions.