undamentalytics Newsletter

Ra Capital Healthcare Fund LP: insider trades

Director, 10% owner at 15 companies we cover. 18 open-market purchases and 3 sales not made under a pre-set plan, reported from October 26, 2015 to July 31, 2026.

Would copying Ra Capital Healthcare Fund LP’s purchases have beaten the S&P 500?

Too few purchases to judge. Only 11 purchases have 12 months of prices after the report; we judge insiders once they have 20. The figures below can swing a long way on a handful of trades. Buying each purchase the day after it was reported, an equal amount each, and holding it 12 months or until they reported a sale would have turned $10,000 on October 27, 2015 into $4,389 by November 2, 2026, −7.2% a year. The copy held shares only 62% of the time, so the fair comparison is the S&P 500 on those same days with Treasury bills otherwise: $30,903, +10.8% a year (the S&P 500 held throughout made $43,799, +14.4% a year). Beta against the index was 0.79. Twelve months after each report, the average purchase was +1.0% against the S&P 500 (median −14.4%), and 36% beat it. Measured from the trade date, the insider’s own timing, the average was +5.8%.

With 296 insiders tested, some will look skilled or unskilled by chance alone: when we replaced each insider’s stocks with random companies bought on the same days, about 5.7 cleared the bar ahead and 23.3 behind. One record on its own proves little.

$0$20.0k$40.0k 201520172019202120232025 $43.8k$30.9k$4.4k
Copying Ra Capital Healthcare Fund LPS&P 500, same days investedS&P 500, held throughout $10,000 copying Ra Capital Healthcare Fund LP’s open-market purchases from October 27, 2015, before costs and taxes, marked weekly. Each purchase gets the same starting stake, bought at the close of the first trading day after the report and sold 12 months later or the day after a reported sale of that stock; uninvested money earns the Treasury bill rate. “Same days invested” holds the S&P 500 only on the days the copy held shares, Treasury bills otherwise.
Return a year, copying
−7.2%
S&P 500, same days invested
+10.8% (held throughout +14.4%)
Time in shares
62%
Sharpe ratio (S&P 500)
0.10 (0.72)
Biggest drop (S&P 500)
−92% (−34%)
Market sensitivity (beta)
0.79
Purchases copied
14

Trade by trade

Ra Capital Healthcare Fund LP: trades against the S&P 500 afterwards
MeasuredTrades countedAverage vs S&P 500MedianWent the right wayYearst-statisticp-valueEvidence
Purchases, 3 months after the report 14 −10.1% −12.9% 43% 9 −1.10 0.30 No reliable evidence
Purchases, 6 months after the report 12 −5.8% −21.6% 33% 9 −1.09 0.31 No reliable evidence
Purchases, 12 months after the report 11 +1.0% −14.4% 36% 8 −0.77 0.47 No reliable evidence
Purchases, 12 months after the trade 11 +5.8% −15.2% 46% 8 −0.38 0.72 No reliable evidence
Sales, 3 months after the report 1 −39.2% −39.2% 100% 1 — — Not enough years
Sales, 12 months after the report 0 — — — — — — Not enough years
Sales, 12 months after the trade 0 — — — — — — Not enough years

“Average vs S&P 500” is the stock’s return including dividends minus the index’s over the same dates, from the close on the first trading day after the report, or from the close on the trade date. Only windows that have finished are counted. For sales, a negative figure means the stock lagged after it was sold, so selling was the right call (green). “Went the right way” is the share of purchases that beat the index, or of sales that trailed it. The t-statistic uses one average per year of reports, because one person’s trades bunch into the same stock and weeks, and needs trades in at least four different years; the p-value comes from the t distribution with that number of years (with four years, a t of 2 has p = 0.14). “Some evidence” means p under 5%, “strong evidence” p under 1% over at least six years.

Companies traded

CompanyTitle on the latest filingPurchasesSalesFirst reportLatest report
Aclaris Therapeutics, Inc. ACRS —40October 26, 2015February 24, 2016
Fulcrum Therapeutics, Inc. FULC —11January 6, 2023December 10, 2025
Tyra Biosciences, Inc. TYRA —20November 13, 2024June 11, 2025
Artiva Biotherapeutics, Inc. ARTV —20July 20, 2026July 31, 2026
Phathom Pharmaceuticals, Inc. PHAT —10April 3, 2020April 3, 2020
Verastem, Inc. VSTM —01June 29, 2020June 29, 2020
Werewolf Therapeutics, Inc. HOWL —10June 16, 2021June 16, 2021
Cytek Biosciences, Inc. CTKB —10March 16, 2022March 16, 2022
Wave Life Sciences, Inc. WVE —10June 21, 2022June 21, 2022
ARS Pharmaceuticals, Inc. SPRY —10September 25, 2023September 25, 2023
An2 Therapeutics, Inc. ANTX —01August 13, 2024August 13, 2024
Janux Therapeutics, Inc. JANX —10March 7, 2025March 7, 2025
Pepgen Inc. PEPG —10September 30, 2025September 30, 2025
Climb Bio, Inc. CLYM —10January 7, 2026January 7, 2026
Adicet Bio, Inc. ACET —10April 13, 2026April 13, 2026

Trades and what followed

Moves are against the S&P 500; green means the trade went the insider’s way.

ReportedTradedCompanyTradeValue3 months after report12 months after report12 months after trade
July 31, 2026July 29, 2026 ARTV Purchase $455,726 −61.0%not yetnot yet
July 20, 2026July 16, 2026 ARTV Purchase $1,432,119 −43.8%not yetnot yet
April 13, 2026February 18, 2026 ACET Purchase $1,603,934 +15.0%not yetnot yet
January 7, 2026January 5, 2026 CLYM Purchase $24,888 not yetnot yetnot yet
December 10, 2025December 8, 2025 FULC Sale $58,377,021 −39.2%not yetnot yet
September 30, 2025September 26, 2025 PEPG Purchase $30,000,000 not yetnot yetnot yet
June 11, 2025June 9, 2025 TYRA Purchase $1,904,002 +12.0%+149.9%+125.4%
March 7, 2025March 5, 2025 JANX Purchase $25,342,965 −21.5%−75.5%−72.7%
November 13, 2024November 8, 2024 TYRA Purchase $19,836,066 −25.4%−14.4%−19.5%
August 13, 2024August 9, 2024 ANTX Sale $3,807,102 not yetnot yetnot yet
September 25, 2023September 21, 2023 SPRY Purchase $8,183,526 not yetnot yetnot yet
January 6, 2023January 4, 2023 FULC Purchase $1,315,286 −81.5%−51.2%−32.8%
June 21, 2022June 16, 2022 WVE Purchase $20,382,112 not yetnot yetnot yet
March 16, 2022March 14, 2022 CTKB Purchase $7,191,456 −4.4%−15.5%−15.2%
June 16, 2021June 14, 2021 HOWL Purchase $4,129,398 +9.1%−60.2%−51.2%
June 29, 2020June 25, 2020 VSTM Sale $2,218,083 not yetnot yetnot yet
April 3, 2020April 1, 2020 PHAT Purchase $2,923,536 −25.7%−42.2%−18.0%
February 24, 2016February 22, 2016 ACRS Purchase $681,524 +0.5%+38.9%+41.0%
January 20, 2016January 15, 2016 ACRS Purchase $155,088 −25.2%−3.5%+14.5%
October 30, 2015October 28, 2015 ACRS Purchase $3,418,800 +59.1%+40.1%+45.7%
October 26, 2015October 22, 2015 ACRS Purchase $75,902 +50.8%+44.3%+47.2%

Open-market purchases and sales of at least $10,000 in companies we cover, from SEC Form 4 filings; sales made under a pre-set Rule 10b5-1 plan are not shown. “Not yet” means the window has not finished or the share price was under $5 at entry. These are the shares’ moves after each trade: they say nothing about why Ra Capital Healthcare Fund LP traded and do not suggest the use of non-public information. How every insider compares · the insider trading backtest.