Rock Springs Capital MIRM Position
Active7-Fund ConvergenceRock Springs Capital increased their position in Mirum Pharmaceuticals Inc. (MIRM) in Q4 2025, holding $60.2M worth of shares across 762,294 shares.
The position was first reported in Q1 2023 and has been tracked across 12 quarterly 13F filings.
MIRM is a convergence signal: 7 specialist biotech funds hold this stock, suggesting high institutional conviction.
There is an upcoming Phase 2 readout for Volixibat in 75 days (Jun 30, 2026), making the timing of Rock Springs's position particularly relevant.
Short interest stands at 12.4% of float with 9.0 days to cover, indicating significant bearish positioning against Rock Springs's long thesis.
About Mirum Pharmaceuticals Inc.
Mirum Pharmaceuticals, Inc., a biopharmaceutical company, focuses on the development and commercialization of novel therapies for debilitating rare and orphan diseases. The company's lead product candidate is LIVMARLI, an investigational oral drug for the treatment of progressive familial intrahepatic cholestasis disease, as well as for the treatment of Alagille syndrome and biliary atresia disease. It also develops Volixibat drug for treatment of intrahepatic cholestasis of pregnancy and primary sclerosing cholangitis. Mirum Pharmaceuticals, Inc. was incorporated in 2018 and is headquartered in Foster City, California.
Full company profile →Short Interest
12.4%
9.0 days to cover
Rock Springs Capital MIRM Position History
| Quarter | Action | Shares | Change | Value |
|---|---|---|---|---|
| Q4 2025 | Increased | 762,294 | +1,168 | $60.2M |
| Q3 2025 | Decreased | 761,126 | -57,080 | $55.8M |
| Q2 2025 | Decreased | 818,206 | -133,559 | $41.6M |
| Q1 2025 | Decreased | 951,765 | -519,799 | $42.9M |
| Q4 2024 | Decreased | 1,471,564 | -108,924 | $60.8M |
| Q3 2024 | Decreased | 1,580,488 | -191,550 | $61.6M |
| Q2 2024 | Decreased | 1,772,038 | -84,526 | $60.6M |
| Q1 2024 | Increased | 1,856,564 | +5,100 | $46.6M |
| Q4 2023 | Increased | 1,851,464 | +30,731 | $54.7M |
| Q3 2023 | Held | 1,820,733 | — | $57.5M |
| Q2 2023 | Increased | 1,820,733 | +25,000 | $47.1M |
| Q1 2023 | New | 1,795,733 | +1,795,733 | $43.1M |
Frequently Asked Questions
Does Rock Springs Capital own MIRM?
Yes. As of Q4 2025, Rock Springs Capital holds 762,294 shares of Mirum Pharmaceuticals Inc. (MIRM) valued at $60.2M. This data comes from their SEC 13F filing.
How many hedge funds own MIRM?
7 specialist biotech hedge funds currently hold MIRM, including Eventide Asset Management, BVF Partners, Tang Capital Management and 3 more. When 3 or more specialist funds hold the same stock, BiotechEdge flags it as a convergence signal.
When did Rock Springs Capital first buy MIRM?
Rock Springs Capital's position in MIRM was first reported in Q1 2023. 13F filings are reported with a 45-day delay, so the actual purchase may have occurred earlier in the quarter.
Is Rock Springs Capital's MIRM position increasing or decreasing?
Rock Springs Capital increased their MIRM position in the most recent quarter, adding 1,168 shares.
Get the weekly biotech signal briefing
Fund moves, convergence shifts, insider buys, and catalyst alerts — delivered free every Monday.
MIRMCompany Page →
All fund holders, insider trades, catalysts, and cash runway
Rock Springs CapitalPortfolio →
Full 13F holdings, sector breakdown, and top movers
Drill into any signal
Fund Convergence
See which stocks multiple specialist funds are buying at once
Catalyst Calendar
Every PDUFA date, Phase 3 readout, and AdCom in one view
Insider Trading
When executives buy their own stock — the strongest bullish signal
Cash Runway
Which biotechs are running low on cash and face dilution risk
Short Squeeze
High short interest + fund buying + upcoming catalyst = squeeze setup
Signal Rankings
Every signal in one composite score — ranked by conviction
Biotech Movers
Stocks with the most signal activity right now across all signals
13F Changes
What top biotech funds bought and sold in the latest 13F filing
Want AI context on every signal? Start free trial →