Rtw Investments 13F: Adds $14M to Castle Biosciences (CSTL) Stake
RTW Investments increased its CSTL holdings by 643,098 shares, now holding 2.76 million shares.
Reviewed by automated data checks against the source filing. How we make and check alerts
Rtw Investments added 643,098 shares to its stake in Castle Biosciences, Inc. ($CSTL), a 30.40% increase, according to a 13F filing with the SEC dated May 15, 2026. It reported 2,758,335 shares worth $57.97 million at the end of the quarter.
Since the filing, $CSTL is up 5.3% after 1 week, up 8.0% after 1 month and up 67.1% to date (from the $19.13 close on May 15, 2026).
CSTL
Castle Biosciences, Inc.
Key Points
- RTW Investments increased its CSTL stake by 643,098 shares, now holding 2.76 million shares valued at $57.97 million.
- Rtw Investments held 2,758,335 $CSTL shares at quarter end, up 30.40% from the prior quarter.
- CSTL shares traded around $21.02 with a recent analyst consensus maintaining a 'buy' rating and targets up to $52.
- Insiders including Derek Maetzold and Ellen Goldberg engaged in buying and selling activities in late May and early June.
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RTW Investments has significantly increased its position in CSTL, adding 643,098 shares in its latest move. This brings its total holdings to 2,758,335 shares, reflecting a 30% increase. As of the latest SEC filing, these shares are valued at approximately $57.97 million.
What Changed in RTW Investments' CSTL Position
RTW Investments' recent filing shows a substantial boost in its CSTL holdings. The firm previously owned 2,115,237 shares and has now increased this by 643,098 shares, resulting in a new total of 2,758,335 shares. This change represents a 30.4% increase in their stake, with the value of the holdings standing at $57.97 million.
Other Institutional Activity in CSTL
In addition to RTW Investments, other institutional investors have also adjusted their positions in CSTL. BlackRock, Inc. reduced its holdings by 122,300 shares, now holding 2,982,946 shares valued at approximately $73.23 million. Principal Financial Group Inc trimmed its position by 37,767 shares, ending with 1,769,877 shares worth about $43.45 million. Portolan Capital Management, LLC cut its stake by 379,180 shares, now holding 1,350,283 shares valued at $33.15 million. Meanwhile, Vanguard Capital Management LLC established a new position with 1,177,522 shares valued at $28.91 million.
Castle Biosciences, Inc. Stock Down 37.8%
Shares of CSTL are trading around $21.02. The stock has seen varied institutional interest, as reflected in the recent movements by major funds. The current market sentiment is supported by analyst ratings, which remain positive.
Insider Buying and Selling at Castle Biosciences, Inc.
Recent insider activities at CSTL include several transactions. On June 1, 2026, Derek Maetzold, the President and CEO, sold 6,214 shares and also bought 6,214 shares at an average price of $2.39. Additionally, he sold 9,836 shares at $20.86 under a planned sale. On May 28, 2026, insiders Ellen Goldberg, Rodney Cotton, and Kim Caple each bought 11,766 shares.
Analysts Set New Price Targets
Analyst firms have maintained positive ratings on CSTL. On May 13, 2026, BTIG maintained its 'buy' rating with a $40 price target. Earlier, on May 7, 2026, Baird reiterated its 'buy' rating with a target of $43. Canaccord Genuity also maintained a 'buy' rating with a $40 target on April 20, 2026. The consensus remains bullish, with a target mean price reflecting strong confidence among analysts.
About CSTL
CSTL operates in the healthcare sector, focusing on providing advanced diagnostic and prognostic tests for various medical conditions. The company is headquartered in the United States and continues to expand its portfolio of medical testing solutions.
Bottom Line
RTW Investments' increased stake in CSTL highlights its confidence in the company's potential. As the 13F filings are backward-looking, this move provides insight into RTW's strategy as of the reporting period. With active insider trading and positive analyst ratings, CSTL remains a stock to watch in the healthcare sector.
Related Filing Alerts
Source: Rtw Investments's 13F filing on $CSTL (May 15, 2026). 13F filings show holdings as of the end of the reporting quarter and may not reflect the fund's current position. Find the original filing: Rtw Investments 13F filings on SEC EDGAR. Written by software, not financial advice. How we make alerts