SC 13G ·Filed Oct 20, 2026
Passive investor 5%+ stake
Actionable Insight • Neutral
Monitor for any subsequent conversion to a Schedule 13D, which would signal activist intent. The stake is sizable but passive — no immediate catalyst.
Latest settled — T+1d
RARE ▲ +0.19% at T+1d
NEUTRAL call +0.19% · α vs SPY +1.37% · entry $15.92 → $15.95
Latest observation: T+2 -4.98% FF3 residual α
T+1d
+0.19%
call +0.19% · α +1.37%
$15.95
settled 6d ago
T+5d
Pending
due 10h ago
T+20d
Pending
in 21d
T+60d
Pending
in 3mo
Price Chart
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Executive Summary
Madison Avenue Partners, LP and affiliated entities filed a Schedule 13G disclosing a 6.4% passive stake in Ultragenyx Pharmaceutical Inc. as of October 13, 2026. The filing indicates no intent to influence control, and the stake is held through Madison Avenue International LP.
Key Financial Metrics
Stake
6.4%
Investor
Madison Avenue Partners, LP
Key Facts
- Madison Avenue Partners, LP and related entities beneficially own 6,307,798 shares of Ultragenyx common stock.
- The stake represents approximately 6.4% of outstanding shares, based on 98,588,873 shares outstanding as of June 30, 2026.
- The filing is a passive Schedule 13G under Rule 13d-1(c), with no intent to change or influence control.
- The reporting persons include Madison Avenue International LP, Madison Avenue Partners, LP, EMAI Management, LLC, Madison Avenue GP, LLC, Caraway Jackson Investments LLC, and Eli Samaha.
- This is a new filing (not an amendment) dated October 20, 2026, with beneficial ownership as of October 13, 2026.
Financial Impact
6.4% passive stake valued at approximately $X (no price data provided in filing).
ownership_percentage
Risk Factors
- Potential future conversion to activist filing (13D) if the investor changes strategy.
- No material financial data or guidance provided in this filing.
Investment Themes
Documents Analyzed
This report is based on 4 SEC documents filed with EDGAR.
| Document | Accession Number |
|---|---|
| SC 13G Filing (Primary) | 0001013594-26-001062 |
| Document: 0001013594-26-001062-index-headers.html | 0001013594-26-001062 |
| Document: 0001013594-26-001062-index.html | 0001013594-26-001062 |
| Document: 0001013594-26-001062.txt | 0001013594-26-001062 |
17 reports for RARE
78% Hit rate @ T+5 Went positive at some point 8 of 9 best @ T+60▲ +48.73%
Filters
Rows
| Type | Now | ||||
|---|---|---|---|---|---|
Oct 20, 2026 7d ago | SC 13G | $15.92 | awaiting T+5 | — | $16.75 (+5.21%) |
Oct 19, 2026 8d ago | 8-K | $15.07 $16.08 | ▲ +6.70% | ▲ +6.85% | $16.75 (+11.15%) |
Oct 14, 2026 13d ago | 8-K | $14.90 $15.92 | ▲ +6.85% | ▲ +6.39% | $16.75 (+12.42%) |
Oct 7, 2026 20d ago | 8-K | $14.89 $14.90 | ▲ +0.07% | ▲ +1.05% | $16.75 (+12.49%) |
Sep 17, 2026 5w ago | Press Release | $14.50 $14.77 | ▲ +1.86% | ▲ +1.01% | $16.75 (+15.52%) |
Sep 2, 2026 7w ago | 8-K | $14.85 $14.30 | ▲ +3.70% | ▲ +2.56% | $16.75 (−12.79%) |
Sep 1, 2026 8w ago | Press Release | $26.53 $14.40 | ▼ −45.72% | ▼ −44.76% | $16.75 (−36.86%) |
Aug 11, 2026 11w ago | 8-K | $26.80 $25.49 | ▼ −4.89% | ▼ −4.48% | $16.75 (−37.50%) |
Aug 4, 2026 12w ago | 8-K | $24.93 $26.86 | ▲ +7.74% | ▲ +7.39% | $16.75 (−32.81%) |
Aug 4, 2026 12w ago | Insider Cluster | $25.81 $26.96 | ▲ +4.46% | ▲ +4.56% | $16.75 (−35.10%) |
Showing 10 of 17
US Market Status
Market Closed — Opens Wed (< 1m)
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