EcoR1 Capital, LLC

CIK 0001587114 · Q1 2026

13F Equity AUM

$2.4B

+6.9% QoQ

Positions

+1 QoQ

AUM Rank

#1,631

Top 13%

Skill Alpha (FF)

+0.1%/yr^ns

No Clear Edge

Rank #2,285 · Top 28%

vs S&P -10.0%/yr (unadj.)

Quarters Tracked

~11 years

Portfolio Concentration

Top 5: 74.1%Top 10: 89.6%Top 20: 98.7%

ZYME24.4%

ANAB18.6%

JAZZ13.7%

CNTA10.8%

CRNX6.6%

AKTIS ONCOLOGY INC3.7%

ORIC3.6%

CGON3.2%

CRSP2.8%

ETON2.3%

Others (19)10.4%

HHI (Herfindahl-Hirschman Index) measures portfolio concentration. Low (<1500) = diversified, Moderate (1500-2500), High (>2500) = concentrated bets.

Sector Allocation

Healthcare95.9%

Unclassified4.1%

Portfolio weight by GICS sector based on latest 13F filing. Sectors below 2% are grouped as “Other.”

Position Sizing

Positions: 29Median: 0.98%Avg: 3.45%

0–0.5%

11(1.9%)

0.5–1%

4(3.1%)

1–3%

6(10.5%)

3–5%

3(10.4%)

5%+

5(74.1%)

Count of positions per weight bucket — (%) = combined portfolio weight

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Portfolio Overlap

Shared: 26Unique: 3vs 20 funds

0.4%Low

Fund positions

7,299

Consensus CUSIPs

Jaccard similarity of this fund’s portfolio vs the consensus of top 20 funds by AUM. Low (<15%) = contrarian, Moderate (15-40%), High (>40%) = follows the crowd.

Most Similar Funds

Top 9 benchmark funds with highest portfolio overlap (Jaccard similarity)

VANGUARD CAPITAL MANAGEMENT LLC

0.7%

GEODE CAPITAL MANAGEMENT, LLC

0.7%

BlackRock, Inc.

0.6%

BANK OF AMERICA CORP /DE/

0.4%

FMR LLC

0.7%

MORGAN STANLEY

0.4%

STATE STREET CORP

0.6%

VANGUARD PORTFOLIO MANAGEMENT LLC

0.6%

JPMORGAN CHASE & CO

0.4%

Jaccard similarity per fund: shared CUSIPs / (fund A + fund B − shared). Higher values indicate more similar portfolios.

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Position Changes This Quarter

New10Increased4Decreased4Exited9

New Positions

AKTIS ONCOLOGY INC3.7%

+4.8M

RLAY0.8%

+1.9M

ERAS0.6%

+900K

EIKON THERAPEUTICS I…0.3%

+733K

REPL0.3%

+1.0M

ZURA0.3%

+1.2M

PHAT0.3%

+625K

PRLD0.1%

+947K

STOK0.1%

+100K

HELIX ACQUISITION CO…0.1%

+200K

Increased

MREO0.2%

+5.5M(+70%)

CNTA10.8%

+3.3M(+106%)

ETON2.3%

+141K(+7%)

CGON3.2%

+37K(+3%)

Decreased

MBX1.0%

-1,346,604(-63%)

XNCR1.1%

-1,135,612(-34%)

IBIO0.1%

-645,000(-29%)

ATRA0.0%

-473,590(-83%)

Exited

-2,855,590

-334,380

-450,000

-2,625,000

-4,002,847

-1,660,000

-963,333

-675,000

-325,000

Quarter-over-quarter changes compared to prior 13F filing. New = first appearance; Exited = no longer held.

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Holdings

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